Baby blowing bubbles

Co

My baby is almost 9 weeks old and is bottle fed. She drinks greedily and can usually take 3-4oz in around 5 minutes but the past few days I’ve noticed she’s blowing bubbles back into the bottle so when she gets to the last oz or so it’s near enough pure bubbles and I believe this has caused her to have wind. I’m wondering if it’s time to change to a faster flow teat? Or could something else be causing this?