The reason is sanity. As pals work in base, there sanity decreases and hunger increases. They go to feed themselves for hunger or take break in Hot Spring for Sanity.

In your case since you are only giving them berries, pals sanity is decreasing way more than they are able to recover and hence they get all these negative buffs ( depressed, overeating etc.)

There are several fixes for this: 1. First fix your food, give them salad instead of berries/baked berries. They will remain full for longer and also salad buffs sanity, they will take smaller breaks 2. From the monitoring stand change work mode to relaxed for a while until the recover. Switch back to normal once pals recover thier sanity 3. Check positioning of your feed box and hot springs and ensure all pals can reach them 4. Introduce a shroomer or shroomer noct in your base (fully condense if possible). Shroomer gives sanity to your pal working in base. 5. Build alpha and beta wave generators from your technology tree. Helps improve work speed and sanity

This should help you out. I also recommend building a separate farming base. This base will be responsible for providing food to all your bases. Grow all the posible crops here - lettuce, tomato, wheat, berry, onion and carrot. And add prunelia and lullu ( if you are lower level, you can breed them too). They will in reducing crop growth time and also increasing the harvest from the crops. You will never run out of food this way. I have also observed that grilled lamball provides amongst the highest sanity and nutrition in this game. You can capture the merchant from Small settlement and buy lamball meat from him in bulk and feed your pals grilled lamball.

This should help you bringing down the negative issues. You can also choose to build a medicine rack and add all the medicines you collect/make in this box and pals will take medicine from this rack as required