I created an internal application for our company to use that is essentially a directory of staff members. I do most my development in Chrome but the bulk of the users are on iOS (Safari). I always find little nuances that I need to tweak for things to be "just right" on Safari. One example is that in all other browsers (including Safari Desktop) a <input type="search"> will show a little clear button ("X") at the end of the input. Some bug removed it from iOS Safari and we're still waiting for them to resolve the issue. It was reported in 2016 and was acknowledged by Apple [1]...

[1] https://stackoverflow.com/questions/35583503/input-type-sear...