i missed this part when reading the upgrade instructions previously, but the other mint 20 upgrade discussion encouraged me to take a closer look and i saw this in the notes:
The upgrade overwrites files in /etc/ with default configuration files. You can restore files indivually by the Timeshift snapshot you made prior to upgrading.
that would give me pause if i were in your position and considering upgrading. i don’t know everything that /etc contains, but it probably has your printer configuration (which i know was a frustration in the past) as well as any installed fonts or icons.
that also reminded me that since
and there have been some printer compatibility issues discussed here recently in relation to mint and ubuntu 20, i would recommend grabbing a copy of your printers.conf file in /etc/cups/ if it exists (you can check in your file manager). since you have an hp (maybe still do?) and if you use hplip there may be a different location, but checking it out certainly wouldn’t hurt.
that file usually only has root read and write permissions so you may need to sudo cat /etc/cups/printers.conf and then copy the output to a regular text file.