First: High population, or overpopulation, does not reduce stability.

In Steam and Stadia Opendevs, each population in a city will cost a bit stability. This is a great way to balance out the natural population growth, introduces meaningful stability management, and also an adequate presentation of the reality - IRL, pre-modern cities were not a good place to live due to unhygienic water sources and unable to properly deal with sewage. The in-game stability family infrastructures, Public Fountain-Aqueduct-Sanitary Sewer, are all directly echo with this historical fact as well as the corresponding game mechanic. Moreover, Food surplus will also contribute to stability.

However, in the Lucy Opendev, the entire population-stability mechanism is gone. Overpopulation only has a food penalty, which is nothing compared to the food yields. In most of the playthroughs, every city can pump out a new population every turn for at least 50 turns as long as the food infrastructures are in place, without any penalty whatsoever. As a result, both population management and stability management become non-exist beginning from the late Classical Era, which is unfun and unrealistic.

Second: Civic choices unlock much slower than civic points.

In Steam and Stadia Opendevs, the pace of civic choice unlocks feel very natural. Build several Farmers Quarters will give you Land Ownership civics (public or private land), meet one or two Independent People will give you IP civics (hire them or assimilate them). Naturally grow and manage your empire will always give you civic choices, and you need to decide which civic to choose first, as you only have very few civic points.

However, in the Lucy Opendev, the thresholds of hidden requirements/triggers of the civics seem to be raised heavily. Build several Farmers Quarters are not enough, you need to spam at least 5 of them across different cities in order to figure out what land rights my people used. The Religion Tolerance civic (respect other religion or denounce them as fake beliefs) hardly shown up despite your religion is devouring other faiths. The Slavery civic never unlocks in my playthroughs of Lucy, while in Stadia Opendev it unlocks every time somewhere into Classical Era. And finally, in the Early Modern Era, the rulership of my empire is still a small council established Ancient Era - the 2nd tier Rulership civic just refuse to unlock - as if my empire never need constitutional changes.

    ← My empire really embraces the traditional institutions here. 

What make things worse is that since there is no need to manage stability, high stability means one will always have fast civic point gains, but the civic choices unlock very slowly. As a result, it is very easy that one generates nearly 30 civic points till Early Modern Era but only unlocked about 10 civics. The spare 10+ civic points just sit there and have nowhere to go, which is absolutely absurd.

Therefore, my suggestions are:

1. Bring back the stability penalty for population, but with a twist. Currently, each city does have a soft population limit, which can be increased by attaching new territories. If the population number violates this cap, give it a strong stability penalty per population. If not, the stability penalty can be very small. Only allow late game stability civics (there are some +200% and even +500% stability civics) and infrastructures (there are Sanitary Sewers and Hospitals) to counter the overpopulation stability sink.

2. Reduce the requirements of civic unlocks, make the pace of civic unlocks more natural. In any case, the gaining of civic points should not be super faster than civic unlocks.