@Pipeline Thank you for the suggestion but that is not my point. I don't want to run the 2020 version of BIAB. I'm not even entitled to do it since I didn't pay for it. But I do want my fully licensed and paid for version of BIAB 2019 to run on Big Sur before I decide if I want to keep spending money on future releases of BIAB.

@PGMusic Could you kindly shed some light on this issue please? Will all users be forced to upgrade to BIAB 2020 to have a working version of the program? If so, will it happen every time Apple releases a new version of macOS?