Time Machine no longer works in Catalina 10.15.5

When moving a whole version like Mojave to Catalina it is often cleaner to either get a new disk or to use Disk Utility to erase the disk (and format to Mac OS Extended (Journaled)

https://support.apple.com/en-us/HT202784#format

try using recover to reinstall os 10.15.6. 10.15.5 broke time machine. 10.15.6 may have fixed it in some cases. the normal update process doesn't do the job. apple support has a good description of reinstall. I had to do it to two Macs. now time machine works correctly.

I didn't find that anywhere online. spent a lot of time with apple support and it was mentioned. they also told me that updating to 10.15.6 would fix it "most" of the time. that didn't work in my case. as soon I reinstalled 10.15.6 using recover my time machine works as advertised.

I wasn't aware that 10.15.5 broke time machine. Can you give us a web link to that?