Profile picture at center of lock screen

System Preferences >> Users and Groups and unlock the Padlock lower Left with computer password. Click on you User Account and then the picture in question. An Edit should appear and change of remove the picture.

Once done, re-Lock the padlock.

Sounds like you have FileVault enabled since you describe the two different login screens. You cannot set the FileVault screen to not show the user account login image. It will not follow the settings for the login window as jeffreythefrog indicated.

The FileVault screen should not show for very long as it will shutdown if nobody decrypts the drive.

if you're OK with being "assaulted" with the garish purple and pink monterey wallpaper on the login screen, you can go into SystemPreferences > Users&Groups > Login Options and set "Display login window as:" to "Name and Password", then no account picture will be displayed on the login screen.

just make sure to verify your account NAME as well as your password (for each account) before signing out as you will need BOTH to login afterwards..