Huge sudden drop in public order and income (Medieval 2 Eras mod)

[IcyRuler]

So I was just playing away on the Medieval 2 Total War Eras mod, playing the version that starts in 970. I end my turn, and suddenly on the next turn, a big number of my cities go from 100%+ public order to way less. Also income dropped substantially. The weird thing is, it doesn't affect every city. Only cities/towns with "royal buildings" are affected (I play as the Kingdom of Duklja, aka the Serbians. This faction can construct special buildings with a golden crown next to them, like the Royal Hall and Balkan Town Watch).

Upon closer inspection, it seems that all the positive bonuses for public order severely decreased, in particular the "buildings of entertainment, fun, culture and the maintenance of good order". So is it possible that these royal buildings somehow break my game?

On a sidenote, my faction leader died one turn earlier, and there was this message about coronation (of the next faction leader) not being possible or something like that, unless I went to Ras (one of my settlements). I can't fully remember what it said since it has been a little while, but I did get a new faction leader anyway. If this is somehow a game mechanic, it went completely past me

If anyone knows what is going on, please let me know! I've had no issues with this mod so far and it has been great fun, and I really hope I can finish the grand campaign! Thank you in advance

[IcyRuler]

After some more digging, it turns out it IS actually a game mechanic. On my way to the capital now to see what happens!