All Ubuntu releases from 2023 are EOL,
- Ubuntu Fridge | Ubuntu 23.04 (Lunar Lobster) reached End of Life on January 25, 2024.
- Ubuntu Fridge | Ubuntu 23.10 (Mantic Minotaur) reached End of Life on July 11, 2024
which applies to flavors too, including Ubuntu-MATE.
Ubuntu's full LTS development cycle occurs over a two year period, ending in the release of the LTS release.
Development of the Ubuntu 24.04 LTS cycle started after release of the prior LTS (22.04), with three interim releases showing progress, these were 22.10, 23.04 & 23.10, so referring to 22.x/20.x etc makes little sense given 22.04 & 22.10 are from different cycles, and 23.x isn't a release with two releases on an odd year (in April .04 and October .10).
Your details are unclear, which is why I've not responded before; it maybe the same for others.
For specific and useful advice, I suggest being precise with details.
Also please note Ubuntu MATE 20.04 LTS is end of life so many of us will ignore posts about the release, others may still respond (as Ubuntu 20.04 LTS is still in standard support, thus I see what you're running as Ubuntu 20.04 LTS but using the MATE desktop).