Ubuntu Pro is a subscription offering for Ubuntu users who want to pay for the assurance of getting quick and high-quality security updates for Ubuntu. I tested it out to see how it works in practice, and to evaluate how well it works as a commercial open source service model for Linux.\n
I take it your build is dependant on the community-maintained Universe repo?
https://ubuntu.com/security/cves/about#security
https://help.ubuntu.com/community/Repositories/Ubuntu
https://askubuntu.com/questions/1452497/what-are-esm-apps-and-how-do-they-relate-to-ubuntu-pro
If they already to the work for esm-apps repo then they could at least send those fixes over to the universe repo until the release version is EoL one would think. On the other hand I have no idea what lives in universe and what lives in main.
That was a rabbit hole.