Issues with potty training

So my son is mostly potty trained he still wears a pull-up at night and during naptime. He has a bathroom attached to his room that he uses, he has been going poop in his pull-up during naptime and he’ll take off the pull up and put the poop in the toilet. As glad as I am that he knows poop goes in the potty how do I deal with this? I put him on the potty before naps and after but he still seems to poop a little. 🤦🏼‍♀️ why is potty training so “fun”