I don't know what they mean by buggy. We've had a few problems, but not many. I would dread having to move. The grass is always greener until you get there and find out the quirks of the new software are just the same as the old.
As far as the no longer supported goes, HUH?? They are currently working on a version that will be compatible with PHP8.x, so this is news to me. I've asked in their forum about it.
It seems someone has been misled. Whether it's here or there is above my pay grade. It can't be both ways. I'll make this known to the BOD so they can investigate. Right or wrong, the new software is much more user friendly. I just wish the content from UBB to anything was transferable.