4.5 year old getting in trouble for behavior in daycare PreK. Help!!

My son is 4.5 and incredibly smart. In the past few months he has been acting up more and more at school. He is hitting friends, not following directions, not sitting and participating in circle time, not respecting friends personal space, not keeping his hands to himself, telling teachers no when they try to redirect or correct his behavior, jumping on his nap mat at nap/rest time and generally being disruptive to the learning environment. Some days he does great with no issues but other days he just cannot keep it together. I had to go pick him up early because they just couldn't handle it anymore one day. We talk to him until we are blue in the face about it, try to find out what's going on but are getting nowhere (I know he's 4, I'm not expecting him to behave like an older child would).

I'm looking for tips and suggestions of things to try to help him be successful at school. We have sticker charts at home for prizes, offered him a special prize if he gets no write ups or reports about his behavior. Neither have worked. We talk about having helping hands and listening ears.

Help!! I feel like I am failing him 😔 I have an actual college degree I'm child development and am still at a complete loss of what to do.

Thank you all in advance!!!