I create websites for the healthcare industry. I know exactly what I'm saying. There are some clients that I still need to write IE7 fallbacks for - and a single client that I still write IE6 fallbacks for. Lucky for me our contract has dropped IE7-9 support by default unless it is specifically requested by the client.
Apologies, but offhand I can only think of flexbox issues (specifically related to wrap/min-width, which has been fixed in version 11) and with interactive form validation (which was only just fixed in version 10 or 10.1). I run into various issues when testing on iPhones and the largest section of edits caught in any internal QC are always iPhone/Safari related. With relative certainty nowadays - if it works in Firefox, it works in Chrome and Edge. But then I always need to write some workaround or another for Safari.
The biggest issue is that even when these bugs are fixed - I still need to support them for an extended period of time because for whatever godforsaken reason, Safari updates are tied together with operating system updates. Want the newest Safari? Buy a new iPhone. It's the Windows XP/IE8 problem. Where IE8 had to be supported only because many users were still using XP and couldn't upgrade to IE9 even if they wanted to.
Safari is not an evergreen browser and that's a fair criticism.
However, you can run the latest browser and OS (and most people do) on a 5 year old device, which is about as much as the battery will last anyway. The situation is much worse on Android.
Apologies, but offhand I can only think of flexbox issues (specifically related to wrap/min-width, which has been fixed in version 11) and with interactive form validation (which was only just fixed in version 10 or 10.1). I run into various issues when testing on iPhones and the largest section of edits caught in any internal QC are always iPhone/Safari related. With relative certainty nowadays - if it works in Firefox, it works in Chrome and Edge. But then I always need to write some workaround or another for Safari.
The biggest issue is that even when these bugs are fixed - I still need to support them for an extended period of time because for whatever godforsaken reason, Safari updates are tied together with operating system updates. Want the newest Safari? Buy a new iPhone. It's the Windows XP/IE8 problem. Where IE8 had to be supported only because many users were still using XP and couldn't upgrade to IE9 even if they wanted to.