See Upgrade to .NET 9 by BNAndras · Pull Request #49 · exercism/vbnet-test-runner · GitHub.
This bug in XUnit affects the test suites for several exercises that compare arrays. The .AsEnumerable() workaround seems to be working on the few exercises I’ve checked.
There are about twenty tests failing so far, and those appear to be for Bob and Two-Fer where there’s an ambiguous match exception for comparing two strings. Compiling xunit.assert with XUNIT_SPAN define results in ambiguous calls · Issue #2793 · xunit/xunit · GitHub seems to be possibly related. TwoFer.Speak().toString() seems to be sufficient to make the ambiguous match problem go away.