It is very stagnant for sure.
My guess to this, is that Nelson started off strong and very committed to getting Unturned II developed. People were pretty much the same, there were like, 10 posts a day, some very good, thought-out and interesting ideas with thorough explanation and etc. Thing is, people that were REALLY interested in Unturned II were sort of, “jumping ship” from 3.0 to II and expected 3.0 to slowly die out, as Unturned II got developed.
This last year or last 2 years even, it seems that 3.0 is still going pretty strong and as you said, things from Unturned II start to go over to 3.0. I think that Nelson is trying to manage Unturned II and 3.0 at the same time, trying to develop the new game while trying to please the 3.0 community with things like curated maps, bug fixes, optimization and the network overhaul that’s being done right now.
I honestly believe that 3.0 should’ve been left alove after some extensive QoL improvements and optimization, so as to keep 3.0 a well-functioning game and then focus on Unturned II, since that not only requires building from the ground-up, but also learning the new engine and other stuff. That’s not the case however.
And so, here we are. 3.0 still being worked on about weekly or monthly, Unturned II has a big pile of features and implementations yet to be developed, the community burned through their ideas (note, GOOD ideas, original ideas) and everything’s slowed down to a halt or a near-halt. Not very good state to be in. If Nelson did have a team by the time Unturned II started development, he could’ve let some people work on 3.0 while him and couple more were working on Unturned II. One man can’t juggle those two and get even progress at the end of month on both games. I guess one thing is to let the guys that worked on the console port (no idea why this thing even existed in the first place, but i digress) work on 3.0, but i don’t know how this will sit with the community.
EDIT: Note that i’m fully aware of why Nelson CAN’T have a team without drastically changing 3.0, i’m putting the team idea out there as a hypothetical thought.