My baby no longer sleeps at night after potty trained. Once she gets up to pee she doesn't go to sleep?

Training. It is a matter of re-training your child to go back to sleep after waking up. Enforce to your baby before going to sleep that if she wakes up at night to pee to go back to sleep. When she wakes up, take her back to bed and enforce not getting out of bed. Do that every night as routine. She will get used it to it.
Make sure. That the room is dark, quiet, without televisions, radios etc., especially if the problem is that she is distracted after she wakes up. The environment needs to be boring and there shouldn't be anything to do except sleep. If she's old enough to be potty trained, then she's also old enough to understand that, except for her trip to the potty, she's not allowed to play or be actively up at night.