Lock icon ghosting
Hi, for some reason my Mac insists on displaying this ghost image of some kind of lock icon. It's just a partial square in the top right of my screen (more visible on a dark background). It doesn't appear on the lock screen, only once I sign into my account. I've ruled out the display since it persists despite whatever changes I make to the display settings. It's probably some app that got into a bad state, but I can't figure it out. Any ideas?
MacBook Pro 14″, macOS 14.4