Michalis KamprianisWell, here it is. Ubuntu Pro is now required for updates in the Universe repository, even on LTS systems. That was not the case in the past, as our friend GPT is telling us (GPT's knowledge stops in 2020).
Furthermore, and although English is not my native language, I'm sure that the following doesn't make sense.
Because if you are committed to create the update for the Pro customers, then the effort is already made, so it should be available for all customers.