Sources for an app randomly appeared in header on Updates tab

Fedora 34, gnome-software-40.1-2.fc34.x86_64.

This randomly happened today when opening GNOME Software and switching to the "Updates" tab:

I have tried closing the Updates tab and opening it again, but it was the same.

This is the only suspicious thing that I was able to find in logs: gnome-software[2603]: Called switch_to(details) when in mode updates

I have also tried killing gnome-software and running it with --verbose, but the problem did not appear anymore.

This is actually the second time this issue happened on Fedora 34 (but maybe it was on main GS page, not Updates the other time). I am not sure what causes it, the only thing I remember is that I had a details page for Tremulous opened today using "Show Details" from Shell Overview.