Hey @crinrict
That's correct, the pop up notifications were the first sign but also the fact that my /Sims 4 folder was filling up with lastException.txt with or without mods/cc in /Mods. As far as I could see, there were no negative effects while my sim was in the apartment, I don't know if the error would change or have different effects if my sim were, for instance, involved in the protest or in the Spice District square area.
I wanted to report it because I noticed there was nothing else related to Protests or the Carry Sign on the City Living lists. So this way if others notice this they can know that it is a game bug/error and not a result of something else they did in game. It happens on its own as a result of the autonomous protests.
Thanks for taking a look!