In the latest release, we removed the code that forced the SDK repo to always run tests through dart instead of the test runner. It turns out there are quite a few tests in the SDK that fail when run through the runner.

Some are being discussed in dart-lang/sdk#60437 (comment), but I also found some analysis server integration tests fail too (unsure if this is Windows-specific or not, but I suspect not):

We should first try to update these tests to work with the test runner, but if it proves not to be trivial, we should consider putting the flag back for now.