I just wanted to ask especially regarding the TestFlight app if there were any changes regarding pulsation animations or else? I noticed that the effect stopped working on iPhone and iPad (was working until then) but on desktop it is still working?
I tested it on a simple card template and the flashing worked correctly, so the issue probably lies somewhere else in your card template. I recommend you try cutting out parts of your template to isolate what’s causing the problem, after confirming you can’t reproduce the issue in a simple front/back with that styling added.