I spent a while spawning colonists and dosing them and honestly right now the mutagen is extremely wild. Some people get up to 7 mutations leaving them somewhat incoherent, especially when many are negative (like a young woman who lost BOTH her legs).

This can, or can not, be fixed, but as a suggestions I would like to see maybe higher quality mutagens. Like the existing one is super unpredictable, but still good for using on characters that you may or may not recruit.

Perhaps much rarer there could be a mutagen that lasts less time and has a much greater chance of positive effects. Or similar to the old mod we could get themed mutagens, although I recognize that would be a lot of work.

As for sheer balance: right now mutating a pawn feels like a net negative, especially in early game. This is because they often end up with 2 to 4 negative traits. Dementia seems very common and it can kind of ruin a pawn. Carcinomas are extremely thematic so I kinda like that they show up a lot. Perhaps blindness or loss of hearing could not spawn if a positive trait was applied (similar to the old mod) so you do not get for example cat ears and hearing loss (sad trombone).

As for sheer power I THINK the positive traits could be OP but it would require a longer playthrough to get a real sense of them. Also it would be nice if 'fur' had a different drawback similar to the 'sweat glands'. A furry character is in real trouble during a heat stroke, it is surprising what a few degrees will do.

I agree with Lugaru. It seems like the base serum is just mostly negative. A few missing limbs or cancer I can deal with, but hypersensitivity where the pawn is permanently disabled due to pain, or various brain injuries that render them useless even with brain implants, doesn’t make any of the benefits worthwhile (though it is good for prisoner experimentation).

Whether rebalancing the serum itself or just one or two variants with tweaked probabilities and higher cost.

Also overriding existing mutations for the same dose is an issue (not sure if solvable though), basically have someone’s arm mutant 5 times or similar instances.

Thank you for your suggestions, sadly i can't really tackle issues like mutations overriding each other due to the way the function i used works, which is included in the base game and uses a "Mean time to happen" system with a counter. Changing this would require me to invest lots of time, which i don't have atm due to upcoming exams.
But i drastically decreased the duration of the mutagenic reaction which should decrease the amount of mutations developed (3 days -> 1.25 days). Please let me know if there are any issues.

considering how those mutations are generally cheap way to make an OP pawn I believe this mod is very balanced and I'd add even more weird negative mutations

Make it so theres a mutation minimum, one of my colonists didn't get a single mutation from a serum.