Menu Bar Display icon has disappeared from the macOS Menu Bar
Looks like you have a lot of third-party widgets in your menubar. That's not inherently bad, but I'd suggest rebooting into safe mode and attempting to reproduce the behavior there.
Whether you can or cannot reproduce it, there's a chance this will resolve the behavior when you reboot again into normal mode. It's magical voodoo when this happens, but it has worked for me on similarly mysterious problems in the past.
If the problem disappears in safe mode and returns when you come back to regular mode, try disabling your third-party menubar widgets one at a time.