Best answer
CarefulTrainer
It's because you're not taking proper care of them, simple as that. Make sure your Pals have enough food, rest, and happiness. Neglect is the fastest road to a sick Pal.
All answers
GamerRealist
Actually, it's a cool feature that adds realism to the game. Just make sure to stock up on remedies and keep your Pals' spirits up!
PixelWrangler
Pals in Palworld can get sick for a few reasons, sort of like how things go in the real world but with more pixels! They might catch a cold if you leave them out in bad weather for too long, or they could get ill from battling too much without rest. Always keep an eye on your fluffy (or scaly) friends' needs!