zellij is amazing in terms of UI/UX, but in my experience not as stable as the older options. Which is understandable, screen and tmux have had decades to sort things out, but it does mean that given the general messiness and complexity of remote network connections (which is the most common use case), running into these rough edges is not difficult at all.
I feel like zellij is the future of terminal multiplexers, and I like using it in my personal machines, but I stopped using it for work after a while.
* Can't move tabs (fixed position)
* sixel support with iterm2 is meh. Yes, it shows image, but it does not look good.
* Support for undercurl seems to be missing.
* I need to sacrifice some other functionality I have in tmux.
Yes, I get some extras but it is not ready yet for me personally.