It seems that the fix for MC-121772 only affected hotbar scrolling; as of 24w13a scrolling while holding shift still does not work in menus and in-game GUIs, nor does it work when attempting to change the spectator fly speed while descending. Interestingly, this only affects scrolling with a mouse; scrolling with a trackpad works fine.

As I stated in my comment on MC-266429, holding shift causes macOS to report horizontal scrolling instead of vertical scrolling. I imagine that the fix for MC-121772 involved adding special logic to handle horizontal scrolling (causing MC-267014 in the process); now this just needs to be implemented across the rest of the game.