diff --git a/dio/CHANGELOG.md b/dio/CHANGELOG.md
index 9ed27486d..0c275cbd5 100644
--- a/dio/CHANGELOG.md
+++ b/dio/CHANGELOG.md
@@ -5,7 +5,7 @@ See the [Migration Guide][] for the complete breaking changes list.**
 
 ## Unreleased
 
-*None.*
+- Raise warning for `Map`s other than `Map<String, dynamic>` when encoding request data.
 
 ## 5.3.3
 
diff --git a/dio/lib/src/adapters/browser_adapter.dart b/dio/lib/src/adapters/browser_adapter.dart
index eab026f17..399113c76 100644
--- a/dio/lib/src/adapters/browser_adapter.dart
+++ b/dio/lib/src/adapters/browser_adapter.dart
@@ -2,7 +2,6 @@ import 'dart:async';
 import 'dart:convert';
 import 'dart:html';
 import 'dart:typed_data';
-import 'dart:developer' as dev;
 
 import 'package:meta/meta.dart';
 
@@ -10,13 +9,7 @@ import '../adapter.dart';
 import '../dio_exception.dart';
 import '../headers.dart';
 import '../options.dart';
-
-// For the web platform, an inline `bool.fromEnvironment` translates to
-// `core.bool.fromEnvironment` instead of correctly being replaced by the
-// constant value found in the environment at build time.
-//
-// See https://github.com/flutter/flutter/issues/51186.
-const _kReleaseMode = bool.fromEnvironment('dart.vm.product');
+import '../utils.dart';
 
 HttpClientAdapter createAdapter() => BrowserHttpClientAdapter();
 
@@ -161,21 +154,17 @@ class BrowserHttpClientAdapter implements HttpClientAdapter {
           }
         });
       }
-    } else if (!_kReleaseMode) {
+    } else {
       if (options.sendTimeout != null) {
-        dev.log(
+        debugLog(
           'sendTimeout cannot be used without a request body to send',
-          level: 900,
-          name: '🔔 Dio',
-          stackTrace: StackTrace.current,
+          StackTrace.current,
         );
       }
       if (options.onSendProgress != null) {
-        dev.log(
+        debugLog(
           'onSendProgress cannot be used without a request body to send',
-          level: 900,
-          name: '🔔 Dio',
-          stackTrace: StackTrace.current,
+          StackTrace.current,
         );
       }
     }
@@ -262,13 +251,11 @@ class BrowserHttpClientAdapter implements HttpClientAdapter {
     });
 
     if (requestStream != null) {
-      if (!_kReleaseMode && options.method == 'GET') {
-        dev.log(
+      if (options.method == 'GET') {
+        debugLog(
           'GET request with a body data are not support on the '
           'web platform. Use POST/PUT instead.',
-          level: 900,
-          name: '🔔 Dio',
-          stackTrace: StackTrace.current,
+          StackTrace.current,
         );
       }
       final completer = Completer<Uint8List>();
diff --git a/dio/lib/src/compute/compute_io.dart b/dio/lib/src/compute/compute_io.dart
index 71b4d5158..f45646bfe 100644
--- a/dio/lib/src/compute/compute_io.dart
+++ b/dio/lib/src/compute/compute_io.dart
@@ -22,17 +22,16 @@ import 'dart:async';
 import 'dart:developer';
 import 'dart:isolate';
 
+import '../utils.dart' show kReleaseMode;
 import 'compute.dart' as c;
 
-const _kReleaseMode = bool.fromEnvironment('dart.vm.product');
-
 /// The dart:io implementation of [c.compute].
 Future<R> compute<Q, R>(
   c.ComputeCallback<Q, R> callback,
   Q message, {
   String? debugLabel,
 }) async {
-  debugLabel ??= _kReleaseMode ? 'compute' : callback.toString();
+  debugLabel ??= kReleaseMode ? 'compute' : callback.toString();
 
   final Flow flow = Flow.begin();
   Timeline.startSync('$debugLabel: start', flow: flow);
diff --git a/dio/lib/src/interceptors/imply_content_type.dart b/dio/lib/src/interceptors/imply_content_type.dart
index a26015abc..6664d323d 100644
--- a/dio/lib/src/interceptors/imply_content_type.dart
+++ b/dio/lib/src/interceptors/imply_content_type.dart
@@ -1,16 +1,8 @@
-import 'dart:developer' as dev;
-
 import '../dio_mixin.dart';
 import '../form_data.dart';
 import '../headers.dart';
 import '../options.dart';
-
-// For the web platform, an inline `bool.fromEnvironment` translates to
-// `core.bool.fromEnvironment` instead of correctly being replaced by the
-// constant value found in the environment at build time.
-//
-// See https://github.com/flutter/flutter/issues/51186.
-const _kReleaseMode = bool.fromEnvironment('dart.vm.product');
+import '../utils.dart';
 
 /// {@template dio.interceptors.ImplyContentTypeInterceptor}
 /// The default `content-type` for requests will be implied by the
@@ -34,17 +26,12 @@ class ImplyContentTypeInterceptor extends Interceptor {
       } else if (data is List<Map> || data is Map || data is String) {
         contentType = Headers.jsonContentType;
       } else {
-        // Do not log in the release mode.
-        if (!_kReleaseMode) {
-          dev.log(
-            '${data.runtimeType} cannot be used '
-            'to imply a default content-type, '
-            'please set a proper content-type in the request.',
-            level: 900,
-            name: '🔔 Dio',
-            stackTrace: StackTrace.current,
-          );
-        }
+        debugLog(
+          '${data.runtimeType} cannot be used '
+          'to imply a default content-type, '
+          'please set a proper content-type in the request.',
+          StackTrace.current,
+        );
         contentType = null;
       }
       options.contentType = contentType;
diff --git a/dio/lib/src/transformers/sync_transformer.dart b/dio/lib/src/transformers/sync_transformer.dart
index f2b666299..54da8ccfb 100644
--- a/dio/lib/src/transformers/sync_transformer.dart
+++ b/dio/lib/src/transformers/sync_transformer.dart
@@ -6,6 +6,7 @@ import '../adapter.dart';
 import '../headers.dart';
 import '../options.dart';
 import '../transformer.dart';
+import '../utils.dart';
 
 @Deprecated('Use BackgroundTransformer instead')
 typedef DefaultTransformer = SyncTransformer;
@@ -30,11 +31,21 @@ class SyncTransformer extends Transformer {
 
   @override
   Future<String> transformRequest(RequestOptions options) async {
-    final dynamic data = options.data ?? '';
+    final Object data = options.data ?? '';
     if (data is! String && Transformer.isJsonMimeType(options.contentType)) {
       return jsonEncodeCallback(data);
-    } else if (data is Map<String, dynamic>) {
-      return Transformer.urlEncodeMap(data, options.listFormat);
+    } else if (data is Map) {
+      if (data is Map<String, dynamic>) {
+        return Transformer.urlEncodeMap(data, options.listFormat);
+      }
+      debugLog(
+        'The data is a type of `Map` (${data.runtimeType}), '
+        'but the transformer can only encode `Map<String, dynamic>`.\n'
+        'If you are writing maps using `{}`, '
+        'consider writing `<String, dynamic>{}`.',
+        StackTrace.current,
+      );
+      return data.toString();
     } else {
       return data.toString();
     }
diff --git a/dio/lib/src/utils.dart b/dio/lib/src/utils.dart
index 586b5384d..0073bd7b0 100644
--- a/dio/lib/src/utils.dart
+++ b/dio/lib/src/utils.dart
@@ -1,10 +1,18 @@
 import 'dart:async';
 import 'dart:collection';
 import 'dart:convert';
+import 'dart:developer' as dev;
 
 import 'options.dart';
 import 'parameter.dart';
 
+// For the web platform, an inline `bool.fromEnvironment` translates to
+// `core.bool.fromEnvironment` instead of correctly being replaced by the
+// constant value found in the environment at build time.
+//
+// See https://github.com/flutter/flutter/issues/51186.
+const kReleaseMode = bool.fromEnvironment('dart.vm.product');
+
 /// Pipes all data and errors from [stream] into [sink]. Completes [Future] once
 /// [stream] is done. Unlike [store], [sink] remains open after [stream] is
 /// done.
@@ -30,7 +38,7 @@ Encoding encodingForCharset(String? charset, [Encoding fallback = latin1]) {
 typedef DioEncodeHandler = String? Function(String key, Object? value);
 
 String encodeMap(
-  data,
+  Object data,
   DioEncodeHandler handler, {
   bool encode = true,
   bool isQuery = false,
@@ -43,7 +51,9 @@ String encodeMap(
   // When [encode] is false, for example for [FormData], nothing is encoded.
   final leftBracket = isQuery || !encode ? '[' : '%5B';
   final rightBracket = isQuery || !encode ? ']' : '%5D';
-  final encodeComponent = encode ? Uri.encodeQueryComponent : (e) => e;
+
+  final String Function(String) encodeComponent =
+      encode ? Uri.encodeQueryComponent : (e) => e;
   Object? maybeEncode(Object? value) {
     if (!isQuery || value == null || value is! String) {
       return value;
@@ -85,7 +95,7 @@ String encodeMap(
     } else if (sub is Map) {
       sub.forEach((k, v) {
         if (path == '') {
-          urlEncode(maybeEncode(v), '${encodeComponent(k)}');
+          urlEncode(maybeEncode(v), encodeComponent(k));
         } else {
           urlEncode(
             maybeEncode(v),
@@ -133,3 +143,15 @@ Map<String, V> caseInsensitiveKeyMap<V>([Map<String, V>? value]) {
   if (value != null && value.isNotEmpty) map.addAll(value);
   return map;
 }
+
+// TODO(Alex): Provide a configurable property on the Dio class once https://github.com/cfug/dio/discussions/1982 has made some progress.
+void debugLog(String message, StackTrace stackTrace) {
+  if (!kReleaseMode) {
+    dev.log(
+      message,
+      level: 900,
+      name: '🔔 Dio',
+      stackTrace: stackTrace,
+    );
+  }
+}