Brown circles in gcode viewer -- what do they mean?

I don't understand the brown circles that appear in the GCode viewer running in Firefox on a Mac and Windows 11. I have never seen these for gcode I have sliced. They appear intermittently in files sliced by users in the makerspace I run.

Here is a link to a screen shot:

I searched the forum and Google, but don't see any reference to these. All machines are running Octoprint 1.9.3

Thanks for any light you can shine on this.

I believe those are from the 'cancel objects' plugin. They're marking the different parts you can choose to cancel.

Thank you so much! That explains it perfectly. My mystery is solved and after some experimentation with cancel objects and slicing settings, a plate full of many pieces can be salvaged if one of them begins failure or otherwise shouldn't be printed.