Player retention seems to be a big issue with most servers. Some additional metrics and some additional rewards might help keep people on their servers longer.

In my head its a system with a set number of levels, and at each level there are either cosmetic unlocks or small character perks or marketplace coins that are unlocked along the way. Logging into a server each day gives you a little bit of experience. Maybe each transaction or each calorie spent gives a little bit of experience. Being active when the server shoots down the meteor or completing some objective gives a lot of experience. And then going inactive on a server reduces some experience.

The punishments need to be pretty minor, because people have lives and things come up, but serial leaving every server on the 3rd day should ultimately result in not unlocking the extra perks that come with this system. A little incentive to stick it out when things get a little tricky might help a lot with keeping people on a server rather than just re-rolling the second someone faces a little bit of resistance.

Other bonuses that I can see are that there could be metrics that might also be useful for server admins, maybe if it tracked people leaving early they could restrict joining if they have a big negative score. Or people might be inclined to join games later than the first 3 days because they would be closer to the objectives finishing.

Not a fully baked idea and I'm sure there's a lot of room for improvement, but feels like something should be tried and this is something that would likely be helpful.