.NET 6 tests give warnings on the stderr

[chtenb]

.NET Framework 4.8 tests run without any warnings showing.
Example:

Warning: Could not load "D:\a\Graphviz.NetWrapper\Graphviz.NetWrapper\Rubjerg.Graphviz.Test\bin\x64\Release\net6.0\gvplugin_pango.dll" - It was found, so perhaps one of its dependents was not.  Try ldd.
Warning: dummynode-2 -> dummynode-3: tail is inside head cluster cluster_1
Warning: dummynode-2 -> dummynode-3: head is inside tail cluster cluster_1
Warning: no hard-coded metrics for 'Tahoma'.  Falling back to 'Times' metrics
Warning: node N, port >|< unrecognized

Is this cause by the .NET Framework tests not redirecting stderr properly, or are these warnings actually only occuring on .NET 6.0?