Just a few months ago they renamed and moved around items in the context menu (view image and undo closed tab) and even crippled the functionality of the first one for no reason. I personally have not yet recovered from that change and search for these items every time I need them. Those are just the two I noticed because I use them regularly, I am sure there was more.
And the non breaking changes seem just as annoying, when elements move around or change their appearance, need more/less space etc. The thing is, the browser has been looking nice for years. There is just no need for constant redesigns that change things just for the sake of change.
The replacement for View Image changes functionality, not just UI.
The keyboard shortcut for Copy Link Location changed, something I use countless times each day (plus I can't forget the old shortcut while Firefox ESR still has the old menu).
And the non breaking changes seem just as annoying, when elements move around or change their appearance, need more/less space etc. The thing is, the browser has been looking nice for years. There is just no need for constant redesigns that change things just for the sake of change.