bigsur 11.4 What is this icon in the system status bar？

[snsn]

Nothing happens when clicked

Disappeared after restarting the system

Don't know what it means

 

[DeltaMac]

That's the standard eject symbol, used in the top menu to eject a CD/DVD, when there is an optical drive installed, or an external attached to the Mac.
If you see the symbol, and no actual disk is mounted in the drive, then clicking that icon would not do anything.

 

[haralds]

Actually, the Eject symbol looks like the one attached below.
The above looks like a shift key indicator that could be from some keyboard extension.

 

[snsn]

Finally figured out that it was a capital lock icon.😀
When you press and hold the caps lock key to open the capital lock it will appear in the status bar.