Proofing container: air tight vs simple bowl

After my pizza preparation, from a dough that has spent already a night in the fridge, I always leave about 200g of dough to make a small white pizza to accompany my meal on the day after my pizza night. So I have this 200g piece that has spent 48h in the fridge and that I take out, fold on itself several times to make a ball let it proof again for some hours at room temperature in a greased covered plastic container. Then at baking time, I spread the dough on a bed of semolina flour, trasfer it on a hot cast iron pan and let the bottom cook. After some minutes I sprinkle some oil and salt on the top and finish it under the grill for other few minutes. This is the outcome: soft and nice in the center.

This time I tried to skip the container part and let it proof on a bed of semolina flour covered with just an upside-down bowl. Same baking process but without salt and oil on top. This was the outcome:

Can this be due to the fact that during proofing, in the second case, the dough dried out a bit not being in an air-tight container?

I do no think that this balloon-like effect is due to the lack of "weight" on the surface (no oil and salt). Sometimes I do omit the topping on the air-tight proofed dough as well and it develops more, but never to become a "balloon" this big.