Why does my profile picture in the user login window keep automatically deleting itself?

Hello,

Both my wife and I use our 24" M1 iMac. We both have our own user profiles, each with a separate profile picture. Recently, however, every time I go to the login screen, I notice that my profile picture has deleted itself. I log in, check the system settings for AppleID and iCloud, and my profile picture is still there. Then I change the login screen profile to the correct photo, do what I need to do on the computer, then log out. When I go back to use the computer again, I notice that my profile picture on the login screen is no longer there. I keep doing this again and again hoping that my profile picture won't disappear anymore, but recently it always does. It didn't use to do this. Why does it do this? Why does it disappear? It didn't use to do this two weeks ago. I know it's a minor gripe, but it's very annoying. What can I do to fix it? Thanks in advance.