Its been years and yet this issue still seems to plague ubuntu despite the many versions.
Ubuntu 18.04 show date and time on every screen the old answer here does not work anymore as 'multi monitors add on' is outdated.
How would one do this simple task of showing the top bar across all monitors in a multi monitor set up?
Gnome Shell (unfortunatelly) was not designed to work this way, but an Gnome Shell extension, Multi Monitors Addon, changed its workings in that sense. Unfortunatelly (again), extensions are not official, so may not be regularly updated.
For this specific extension, a fork is available that works on Gnome 40. You cannot (yet?) install that extension from the Gnome Extensions website. However, three terminal commands that you can copy and paste from the website allow to set the extension up.
