During work on #10930 I discovered that there is a problem with Flask and new version of Werkzeug (Flask dependency).

Citing from Stackoverflow:

I had the same problem. It is because Werkzeug 3.0.0 was released and Flask doesn't specify the dependency correctly (requirements says Werkzeug>=2.2.0). This is why, Werkzeug 3.0.0 is still installed and Flask 2.2.2 isn't made for Werkzeug 3.0.0.

Solution: Just set a fix version for Werkzeug such as Werkzeug==2.2.2 in your requirements.txt and it should work.

We need to update our requirements.txt to get a lot of the tests unblocked. Useful list of failing tests from #10930 build: https://source.cloud.google.com/results/invocations/20c95953-b10c-43ea-8cb9-1711e3198379/targets