We’ve had this we just keep baby upright for 30 mins after a feed. It still happens occasionally but. It often.
Depending on which formula you're on, they may have an "anti reflux" one. I'm on cow and gate, and they do, so he's been on that for a day or two now, seems to be helping! It's basically just the normal formula, plus a thickening agent to help it stay down.
Currently going through the same thing with my little girl, spoke to the health visitor and she suggested it could be reflux, so went to the gp and got baby gaviscon but it hasn’t really helped. She’s still really settled and happy after so not sure what it is. Going to speak to the health visitor again next week