Is there a 3-year-old sleep regression?

My little boy who will be turning 3 this Saturday is really struggling to get to sleep at night. His bedtime is 7:30-7:45... I thought sleep regressions were over and done with 🤦🏼‍♀️ the last one he had which doesn't seem like it was that long ago, lasted for 6-8weeks, it was a struggle. But now he's showing signs of another one, he can take anywhere from 2-3hrs to fall asleep and he keeps going out of his room, has been like this for a week or so, his also hitting a lot of milestones at the moment and we are also beginning to potty train him. So I assume having all of this going on is causing him to have sleep issues? Or could I be wrong?