My menu bar is not showing on MacBook Pro mid 2015 Monterey

Hi soeradj224,

Thank you for using the Apple Support Communities! If you test in a new user, is the menu bar also missing? Being able to see if the issue occurs in another user account will to identify if it is something that is affecting your entire system or just one particular user account. To do this, you'll want to set up a Test User account and then try to replicate the issue in that account.

1. Choose Apple menu > System Preferences, then click Users & Groups.

2. Click the lock icon, then enter an administrator name and password.

3. Click the add button (+) below the list of users.

4. Complete the fields shown for a Standard or Administrator account, then click Create Account (or OK).

5. Go back up to the Apple menu in the upper left of the computer and select "Log Out". At the login screen, choose the "Test User" just made.

6. Once inside the Test Account, try to replicate the issue to determine if it just occurs in one account or on the whole computer.

Thank you.

First, uninstall Bitdefender by following the developer's instructions. Anti-virus apps, cleaning/optimizer apps, and third party security software are not needed on a Mac. These types of apps interfere with the normal operation of macOS and usually causes more problems than they solve. macOS has great built-in security especially when combined with the user practicing safe computing habits such as those outlined in this excellent article written by a respected forum contributor:

Effective defenses against malware and other threats - Apple Community

If you still have the issue, then try booting into Safe Mode to see if the issue still exists.

Are the app windows being opened in Full Screen Mode? If so, then the menubar will disappear until you move the pointer to the absolute top edge of the screen.