That may partialy explays what happen in my game. I had a save just before the patch. day 25 of first month.
I start the first NJ diplomatic mission (second diplomatic mission). I had one active nest on the map. I start the mission in a corner with a big building infront of me. At end of the first turn I see nothing. Start of the second turn. I have 2 sirens 3 crabs with heavy machinegun and 2 tritons with shotgun in sight. On my 6 guys, one is mind controled. Seems a bit unfair so soon in the campaign.
After 4-5 restart I successfully survive the first turn in accepatble condition. At the end of the mission I look at the nest. It is now a citadel. I may be wrong but citadel before the end of first month seems early.I never had a single lair. Nest to citadel. Every 1-2 days I have attacks on heaven with sthrengh between 20 and 26. I understand that may have spikes in difficulty but that seems a bit much.
I will relaod my save and destroy that nest before redoing the diplomatic mission. But I fear what seems like a unbalanced progression in difficulty.