Never heard of that. As a matter of interest, which cars are these?
A huge number of cars now have airbags built into the front seats at shoulder height (to protect the head in the event of a side impact, Either that or they are built into tge headlining directly above the door apertures.
On my car (Mazda 6) the leather seats are embossed "SRS" at shoulder height. It stands for Secondary Restraint System. I "think" on fabric seats there is a small plastic plaque with similar embossing, but it's years since I had anything other than leather seats.
I wouldn't worry about any throw or cover inhibiting an airbag deployment, having seen them demonstrated the power they go off with is incredibly ferocious, and powerful. Remember they are designed to restrain a human body travelling at very high G forces