Thank you for the kind words. Not updating is not a decision we have taken lightly. I can’t speak to the specifics because I’m not tech enough to fully understand them, but I believe a major part of the reason for not updating has to do with that migration off Lemmy - that it changes the way data is stored and organized and because of such the migration process (moving comments, threads, etc. to sublinks) would need to be entirely redesigned.
https://beehaw.org/comment/3796083

The instance admins have indicated in the post linked above and in several others that there isn't really any plan to upgrade to the newer Lemmy version given the desire to move to Sublinks.

Edit: There's some more discussion about it in this thread posted earlier today. https://beehaw.org/post/15453474