One of my colonists has negative skill experience
One of the user got negativ informationprovidment ! :-)
Could you please read the sticky "How to report a bug" and try it again ?
This is working as intended. As the most recent public patch, experience will degrade to -1000 before you lose your level. This is to prevent someone hovering at a certain skillpoint gaining and losing it repeatedly.
Another thing that isn't at the patch notes ! :-(
From the most recent patch notes:
"- Pawns will now not lose their skill levels until they fall 1000 XP under zero. This stops pawns from quickly leveling up and down around a threshold."
https://store.steampowered.com/newshub/app/294100/view/4741683783028883223
My apology, i looked for a different thing and oversaw it.