There's currently a penalty to food from Overpopulation.

I certainly didn't see that in my last playthrough. Had a 50+ population city that was growing every turn.  

Check the tooltip:

It's 10 food per pop over the cap. There's currently a bug that adds the saffron benefit to all tiles instead of just districts, so food is HEAVILY inflated, that's why the effect is not very noticeable.

mqpiffle wrote:

I certainly didn't see that in my last playthrough. Had a 50+ population city that was growing every turn.  

I had a costal city pumping 1 pop/turn, but once it overpopulated, it was down to 8%/t

and if you are overpopulated, just build a few buildings but buy them with pop instead, but i fell like this should be a thing to manage under slavery : possibility to sacrifice pops for building construction

Yeah, I never like to use population to create buildings but overpopulation has me like...

Tuco83184 wrote:

Yeah, I never like to use population to create buildings but overpopulation has me like...

Same honestly! 

I went from every pop is valuable to; meh I need this wonder done in a turn after my 3rd playthrough lmao

If I recall correctly, back in the Steam/Stadia Opendev there was a mechanism that would reduce stability in overpopulated cities (cf. see the table in the link).

I do remember that, during the Stadia Opendev, one of my cities was growing uncontrollably (1 pop every turn) and its stability quickly plummeted; it was only after I spend several population into buildings did the stability returned to normal. I haven't experienced anything similar in Lucy Opendev, the stability would remain at a plateau level after the initial food shortage.

In any case, bring in (or bring back) a stability penalty for overpopulation would help a lot with the balancing and the pacing of the game. It can also be connected with historical representation of big cities: Before the development of sewers, big cities can have a high death rate than its surroundings due to unsanitary. We can have a high overpopulation penalty in the beginning of the game, and introduce Sewers as a stability penalty reducing infrastructure in the Industrial Era.

I actually really quite liked how overpopulation was a problem for me in some of my cities just for the THEMATIC storytelling potential it has there, though it'd be nice if it didn't also happen in pretty much all of my big cities at around the same time, and probably also happening at the same time ~every game.
At first I tried to mitigate my population problem by building more farming districts to prop up the max population I could support. That was a little short sighted because it did nothing to actually slow the growth of population. After that I just set my cities to produce units every turn, which in most cases meant I couldn't build my unique unit - the Haras as the Umayyads, because they took 2 or 3 turns to build and my pop was growing +1/every turn. So I was building a mix of regular units and just buying bigger units. The AI did not seem to have my problem at all: The Huns (green), whom I had coralled into one icy mountain city in the SouthWest, was hovering at a nice round plump 0 population. The Zhou (red) were the 2nd biggest on my continent (2 cities of ~ 7 territories) that only ever had something around 7 or 8 units when I declared war on them. The Romans (pink AI) had like ~5 units. Meanwhile I was pushing around 20 going on 30 units, most of which was just for population control.