Safari caused me by far the most issues, back when I was doing frontend in ~2017/2018, in terms of how it complied with web standards (I wasn't as fussed at the standards it didn't support - at least I knew!) and rendered the web application I was working on across desktop, iPad and iPhone.
I spent more time chasing Safari bugs and rendering idiosyncrasies than I did dealing with IE11, frankly.
I spent more time chasing Safari bugs and rendering idiosyncrasies than I did dealing with IE11, frankly.