Re-instate old methods, but as obsolete

src/RestSharp/Options/RestClientOptions.cs

@@ -181,6 +181,16 @@ public RestClientOptions(string baseUrl) : this(new Uri(Ensure.NotEmptyString(ba
     /// </summary>
     public CookieContainer? CookieContainer { get; set; }
 
+    /// <summary>
+    /// Maximum request duration in milliseconds. When the request timeout is specified using <seealso cref="RestRequest.Timeout"/>,
+    /// the lowest value between the client timeout and request timeout will be used.
+    /// </summary>
+    [Obsolete("Use Timeout instead.")]
+    public int MaxTimeout {
+        get => (int) (Timeout?.TotalMilliseconds ?? 0);
+        set => Timeout = TimeSpan.FromMilliseconds(value);
+    }
+
     /// <summary>
     /// Request duration. Used when the request timeout is not specified using <seealso cref="RestRequest.Timeout"/>,
     /// </summary>

src/RestSharp/RestClient.Extensions.cs

@@ -20,7 +20,12 @@ namespace RestSharp;
 [PublicAPI]
 public static partial class RestClientExtensions {
     [PublicAPI]
-    public static ValueTask<RestResponse<T>> Deserialize<T>(this IRestClient client, RestResponse response, CancellationToken cancellationToken)
+    [Obsolete("Please use the async overload with a cancellation token")]
+    public static RestResponse<T> Deserialize<T>(this IRestClient client, RestResponse response)
+        => AsyncHelpers.RunSync(() => client.Serializers.Deserialize<T>(response.Request, response, client.Options, CancellationToken.None).AsTask());
+
+    [PublicAPI]
+    public static ValueTask<RestResponse<T>> Deserialize<T>(this IRestClient client, RestResponse response, CancellationToken cancellationToken)    
         => client.Serializers.Deserialize<T>(response.Request, response, client.Options, cancellationToken);
 
     /// <summary>