What happened?
This painful phenomenon is related to the structure of the piece of meat, if you look at the picture of these 2 chops, the blue arrows are framing the most fleshy part (the "nut" in French).
And the nut is surrounded by a fairly thin, white ring, which is a much fattier part of the meat.
During cooking, especially if it is quick, this fatty part will shrink, without breaking or cutting, and thus contract the nut, hindering its cooking, not great...
What to do to avoid this?
This is fortunately quite simple, just cut the fatty part, incise it in at least 1 place.
A good sharp knife cut the ring (in this picture in 2 different places), and this way you are sure that, when cooking, your piece of meat will remain flat.
Note that this applies mainly to meats like chops, cutlets, or even steak, but more generally to any piece of meat that is a bit flat and you're worried about it shrinking.
To summarize: To avoid deformation when cooking a piece of meat, slit it around the nut.