There are two problems with the LibGit2SharpSource branch of unity2020.3.17f1c1: one is fuzzy reference, which is solved by adding scope before reference, and the other is unsafe code error, I checked allow unsafe code, but still error, see unsafe code error.log

[LikeScientist]

unsafe code error.log ↓ ↓ ↓
-----CompilerOutput:-stdout--exitcode: 1--compilationhadfailure: True--outfile: Temp/LibGit2SharpUnity.dll
Microsoft (R) Visual C# Compiler version 3.5.0-dev-20359-01 (8da8ba0c)
Copyright (C) Microsoft Corporation. All rights reserved.

Assets\Plugins\LibGit2SharpSource\CheckoutConflictException.cs(12,46): warning CS0618: 'MergeConflictException' is obsolete: 'This type will be removed in the next release. Please use CheckoutConflictException instead.'
Assets\Plugins\LibGit2SharpSource\Core\EncodingMarshaler.cs(61,37): error CS0227: Unsafe code may only appear if compiling with /unsafe
Assets\Plugins\LibGit2SharpSource\Core\EncodingMarshaler.cs(94,37): error CS0227: Unsafe code may only appear if compiling with /unsafe
Assets\Plugins\LibGit2SharpSource\Core\EncodingMarshaler.cs(118,37): error CS0227: Unsafe code may only appear if compiling with /unsafe
Assets\Plugins\LibGit2SharpSource\Filter.cs(364,20): error CS0227: Unsafe code may only appear if compiling with /unsafe
Assets\Plugins\LibGit2SharpSource\OdbBackend.cs(62,48): error CS0227: Unsafe code may only appear if compiling with /unsafe
Assets\Plugins\LibGit2SharpSource\OdbBackend.cs(248,39): error CS0227: Unsafe code may only appear if compiling with /unsafe
Assets\Plugins\LibGit2SharpSource\OdbBackend.cs(305,39): error CS0227: Unsafe code may only appear if compiling with /unsafe
Assets\Plugins\LibGit2SharpSource\OdbBackend.cs(407,39): error CS0227: Unsafe code may only appear if compiling with /unsafe
Assets\Plugins\LibGit2SharpSource\SmartSubtransportStream.cs(99,39): error CS0227: Unsafe code may only appear if compiling with /unsafe
Assets\Plugins\LibGit2SharpSource\SmartSubtransportStream.cs(137,39): error CS0227: Unsafe code may only appear if compiling with /unsafe
Assets\Plugins\LibGit2SharpSource\OdbBackend.cs(617,36): error CS0227: Unsafe code may only appear if compiling with /unsafe
Assets\Plugins\LibGit2SharpSource\OdbBackendStream.cs(127,39): error CS0227: Unsafe code may only appear if compiling with /unsafe
Assets\Plugins\LibGit2SharpSource\OdbBackendStream.cs(151,39): error CS0227: Unsafe code may only appear if compiling with /unsafe
Assets\Plugins\LibGit2SharpSource\Core\RawContentStream.cs(13,25): error CS0227: Unsafe code may only appear if compiling with /unsafe

[LikeScientist]

Hurry up and fix it, my brother.