An official ticket has been raised - so now we wait.
Looks like Smart Bear already knew about this. They say:
Thank you for reporting this issue. This problem is already known to us, and our team is working on fixing it. This bug is tracked in COLLAB-9492. When it is implemented it will be listed on the "What's New page"
https://support.smartbear.com/collaborator/docs/general-info/whats-new.html
Consider using a browser other than Firefox, such as Chrome or Edge. On them, this problem does not occur.
It's fixed in the patches 13.12.131202, 14.0.14002, released on 25 Aug 2022
