The PR test has been hit by #4112, which you can see by clicking on the details link of the failed test, then search for "failed". The exact cause is not determined yet.
Also: Tests have been extended on the Windows and macOS runners, and these runners are slooooooooow. We are still fighting flaky tests depending on timing.
So: If you have a reviewed PR like this and you can see that the failures occur only because of flaky tests unrelated to your code, you could select "Merge without waiting for requirements..:" and click on the "Merge..." button in order to merge immediately.