What action should I take when projects don't have matching metadata references?

I got this for every solution, so I started running msbuild /t:Restore on each one first. Now this is only happening with a couple of solutions.

Does it result in degraded functionality? Where should I start looking to fix it?

Generating Some.sln
Workspace failed: Found project reference without a matching metadata reference: Some.csproj
Found project reference without a matching metadata reference: Some.csproj
Workspace failed: Found project reference without a matching metadata reference: Other.csproj
Found project reference without a matching metadata reference: Other.csproj

This warning occurs right after the error lines. Could it be related?

First chance exception System.IO.PathTooLongException: Path: C:\Users\jmusser.nuget\packages\microsoft.netcore.app.ref\5.0.0-rc.2.20475.5\ref\net5.0\C:\Program Files\dotnet\sdk\NuGetFallbackFolder\system.runtime.interopservices.runtimeinformation\4.3.0\ref\netstandard1.1\System.Runtime.InteropServices.RuntimeInformation.dll.dll exceeds the OS max path limit. The fully qualified file name must be less than 260 characters. at Microsoft.Build.Shared.FileUtilities.GetFullPath(String path)

[KirillOsenkov]

Building should be enough, but binlog is an absolute guarantee, in case your build is not exactly the same as the real one (say it needs environment variables etc)

[KirillOsenkov]

Yes there’s more of a chance that it will bring down the dlls so more of the types bind. Otherwise you get broken hyperlinks.