Continuing the discussion from Help requested: issue updating Flair to 3.2-2 (Ubuntu 20.04 in Windows10 WSL):
Hi, I just wanted to let you know that with sudo apt upgrade flair and geoviewer were updated automatically to the new version 3-2-4 from 3-2-2 without the need of applying again the download+compile process. 
Cheers,
Enrico
Dear @enrico.nic,
I think that this behavior can be explained as follows.
When you previously tried to install flair, you first attempted at doing it using the .deb package. Then, after some installation hiccups, we remove the flair directory and installed from the source.
I believe that you computer was still thinking that the package had been installed using the .deb package.
Therefore, it was able to upgrade using the “apt upgrade” command.
Anyway, the only thing that matters is that you can use the latest version of flair.
Dear @amario,
thank you for the possible explanation of what happened. Interesting. And besides being able to update with apt upgrade, there is also – thanks to your patient and detailed help – an alternative procedure in case it fails in a future!
Cheers,
Enrico