I use full screen mode (tab + x) quite a lot. But every time I have to close it and select next task for full screen. I don’t fined any shot key/option to navigate to next/previous tasks directly from full screen mode.
We currently don’t have an option to allow you navigating from one task to another while using the full-screen mode - but I see where you’re coming from with this! I use tab+X a lot and would love to see a function or shortcut implemented to help me navigate tasks without leaving my full screen.
I’ve moved your post to the #productfeedback and I’ll keep you posted as soon as I have an update on my end on this topic!