I think it would be best to make it like this:
Rename "Visualization view" to "Full window mode" ("Enlarged mode"?)
Create an option: "Auto show / hide Now playing when starting Visualization in Docked / Full window mode"
1) Automatically show Now playing when visualization in Docked mode is started.
2) Automatically hide Now playing when visualization in Full window mode is started.
I don't think an automated restoring of the previous state when stopping visualization should be necessary.
Fixed in helium_12.0.14043.0.exe