The blockUi-timeBased-Tests are timing out/failing in CI builds. (See: fluid-work matrix discussion) These tests use a video file for the tests and have had issues in the past related to video format (See:
These test failures actually appeared without any new code being committed to the repo. However, the Ubuntu test runner was updated to use the latest version of FF, v86. The tests have a context awareness check for mp4 support. However in this version of FF it the canPlayType function returns "maybe" instead of "". Which causes the check to pass and the mp4 file to be used. Running FF in Ubuntu requires the webM version to be used.
Interestingly the tests pass after a page reload. Presumably that is enough to tell the browser that the video, in fact, will not play and provide the expected response to the canPlayType function. This is not suitable for the tests though.