There are some major exploits with liberation mechanic, which may need to be fixed. If you liberate an outpost, next turn it become an independent city with 0 population if the outpost have 0 population, which any unit can capture without battle. This allow a player to get like 3 cities at turn 15 or so at a minimal influence cost.

City liberation also allow a serious exploit in which you liberate a city, kill the milita for progress to militarist stars and keep liberating it. Sure you lose a bunch of population but on other hand this allow you to get all militarist stars without need to wage any wars and you can get them pretty much the same turn as you advance to the next era for maximum fame and that can give a huge unfair fame advantage for killing your own population.

this is indeed a big issue and ppl are abusing it

you can basically bypass the need for influence for creating any city at any time of the game play, you can exit neolithic very early with this to have 2 or 3 instant cities while a normal player trying to get 160 inf or very close to it to get a 2nd city...

I found this out on the hard way...

Liberated Outposts should become a IP Outpost.  And IP outposts shouldn’t become cities until a pop of at least 4..and they should keep the pop on becoming a city.

This major bug is still here. It is still working. Please fix it.  :)