How to identify a strange item on my menubar?

After rebooting recently, I noticed a new, unknown icon showing up in my menubar (I'm on Mac OS 10.15.7). Right clicking / double tapping on it does nothing. When I open Activity Monitor, I see icons next to processes but none matches it.

Any idea what process or application this is, or how I can identify it?

1. Open Accessibility Inspector, accessible from Xcode → Open Developer Tool.
2. Under ‘Hierarchy’, click ‘Show’ which will show you the Application Name.
3. Click on the target icon at the top of the inspector labelled ‘Start inspection follows point’.
4. Hover over the item and the pane may show you enough information for you to determine what it is. For example, hovering the Dropbox menu bar item shows "Dropbox <version>" under AXHelp, and hovering Little Snitch shows "Little Snitch Agent" under AXTitle.