Terminal emulators have tabs/windows, tmux has tabs/windows, vim has tabs/windows. All with different keyboard shortcuts and semantics.
I wish this were all unified into a single window/tab/keybinding model. That was easy to code against and write your own interactions for.
I keep hoping I'll see a boundary-pushing project like Kitty do something new in this space.
vim-tmux-navigator[0] is probably the best thing I've installed in my terminal for transparently moving between splits. Using it has allowed switching splits to become so thoughtless that it's automatic as I move my eyes.