The split screen tabs, the color errors (white text on pale yellow backgrounds on sign in bars), not being able to click on buttons on some sites, like my medical providers questions pages, and it's gotten fairly difficult to navagate the settings... I'm an older person, prefer desktop shortcuts to overloaded 'favorites', and open new pages over tabs... But that's just me. I understand almost everything catering to the smartphone generation.
I've used Mozilla / firefox since the beginning ( the 386 era ), & only wish they would have a scaled down 'ludite' setting for us old farts... 🙂
Oh, & I find the AI annoying as hell... For google searches is kinda cool, but having it trying to interpet everything I type is annoying. I had to turn off probably 90% of all the added features, and still can't get some pages to act properly, like they did with all the previous versions.
