When looking at vids of failed tests - we can see "frozen" animations - looks a bit like we see more than one "frame", elements of contents-apps seem to miss, etc. Thus skipping the animations - if doable "easy" could help on the issue.

How we do/dit it finally?

Adding css via UI project with the vaadin theme using the media query:

@media (prefers-reduced-motion: reduce)

And in test-fwk we call the chrome-driver with the flag force-prefers-reduced-motion.

Developer note:

the command line flag
--wm-window-animations-disabled
should do the trick. Most likely can be added as an arg in ChromeOptions at info.magnolia.test.selenium.Selenium#getNewChromeDriver

Just a hunch (perhaps a bit hackish):

• Provide a @DisableCssAnimations annotation you can apply at method level.
• When the driver is created at info.magnolia.test.selenium.Selenium#resolveParameter, use Selenium's ability to execute JS https://www.browserstack.com/guide/javascriptexecutor-in-selenium to inject a custom css, say .disable-css-animations in DOM, something like https://marcgg.com/blog/2015/01/05/css-animations-failing-capybara-specs/
  (see also https://stackoverflow.com/questions/51050533/injecting-css-like-html-through-javascript-into-the-dom)
• If annotation is present, add the custom style to the body of the page still using Selenium's JS executor, e.g. in beforeEach method
• finally remove custom style in afterEach