No drops from rats and wild dogs

I'm playing on a not-premium 1.16.3 server with some friends.
So far we've killed 3 rats and about ten wild dogs, but no one of them all dropped anything besides EXP, the bear just straight off didn't spawn while the piranhas worked perfectly.
Do they have an incredible low drop rate in general? There is a special way to collect the drops? Or it's it simply a bug? 