Stay off Tmux for a couple of months and try again. I've been through that exact scenario. It doesn't feel intimidating, but you still need to brush up.

One thing that zellij does correctly is discoverability. You don't need to even read their documentation to become productive.

Zellij is also reaching feature parity with tmux. But its development seems to be accelerating. Zellij might become the dominant multiplexer soon.