What is this grey bar on my desktop?

[thebluepointe]

Strange grey bar on my desktop just appeared today. No new software installed, computer didn't reboot at all.

• Shows up on main display, whether it is the built-in display on my MacBook Pro 16" M1 or external monitor.
• Stays on Main display...moving main display, moves the bar to that monitor.
• Bar gets smaller/bigger as I scale resolution.
• Changing to dark mode does not change the color.
• Hiding/showing dock does not affect it.
• Stays in same place when switching desktops. On new desktop, it isn't there for a second, then suddenly appears.
• Always on top of any window, but below the cursor.
• Rebooting does not help.

Appreciate any insights.

 

[Saturnine]

No idea but I wonder whether or not it would show up if you were temporarily boot up in recovery mode. Find out whether the issue is built into macOS or whether it’s deeper down.

 

[zarathu]

TRY RESTARTING.

 

[Saturnine]

Rebooting does not help.

TRY RESTARTING.

Welcome to MacRumors.

 

[elptdbi3lYI]

You could try using Accessibility Inspector that comes with Xcode to find out

 

[thebluepointe]

Well, after almost getting used to it, I figured out it was Better Touch Tool. I finally caught it appearing as the app icon appeared in the menu bar. Better Touch Tool is indispensable, so when closing apps to see if they were responsible, I forgot about BTT. It's almost like a system preference, in my mind.

Thanks to all who offered help.