What's with the wine cork bulge?

In three cases, 1 has a little more capacity when it is filled, and the remaining space is relatively small. Hot weather causes the gas to expand and push the plug out.

The problem of wine itself may be that the sterilization is not complete or the apple milk begins to move in the bottle when the fermentation environment is suitable, resulting in flatulence.

Is this bottle dry or sweet? If it is sweet wine, it is likely to start fermentation again in the bottle, thus producing gas, leading to blockage.