Keyboard shortcut problems under Big Sur:

The key combination for the eclipse (…) - Option + ; - still works for me. Boot into Safe Mode according to Start up your Mac in safe mode - Apple Support and see if the problem persists. Reboot normally and check again.

NOTE: Safe Mode boot can take up to 10 minutes as it's doing the following; 

• Verifies your startup disk and attempts to repair directory issues, if needed

• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)

• Prevents Startup Items and Login Items from opening automatically

• Disables user-installed fonts 

• Deletes font caches, kernel cache, and other system cache files

I understand what he's trying to do now. It's possible to do what he wants with a macro app like Keyboard Maestro. One can set a key combination or text string (like the example below using xe) to enter the tag in the info window or any where the cursor is placed:

This is what the Keyboard Maestro macro looks like:

I've found Keyboard Maestro to be my most valuable utility.

Finder will not allow you to assign a keyboard shortcut to the Tags… menu item, whether on its File, or secondary menus. Frustrerende in any language. I am on macOS 11.2.3 and it resists my efforts as it has in the past with prior releases of macOS.

You know, with GUI Scripting I can visually open the File menu and select (blue bar) the Find menu entry (menu item -1), but when I tell it menu item -2, it chooses Eject, completely skipping the existence of Tags… as a menu item. When I tell it to get me the names of all menu items on the File menu, Tags is never returned.