u/Proof_Name960

I'm using Lansinoh glass bottles to formula feed my baby. After mixing the formula, I make sure they're is no foam. As soon as I start feeding it makes the air hissing sound and forms the bubbles at the top.

I'm making sure the air vent is facing towards the roof and it is aligned with the indentation on the shoulder cap.

Is this OK? Do I need to switch the bottles?