This has been happening for a while in every project. I even re-installed MD and I still don't have a clue on how to solve it: when two small pieces are stitched together, they always end up inflating. Even when I open an old file that was working properly in the past, and jun run a simulation (without touching anything else), all the hems and patches inflate, which didn't happen before.
The only thing I noticed that makes a difference is turning off the " Vertex-Vertex" in Proximity Detection (Under Simulation Settings). But then the fabrics don't collide with each other and just slide through.
I really don't know what to do hand how to solve this.
Thank you for your attention!