The pictures describe this better, but in words: when a carpet is placed on a block that is pushed away by a sticky piston, the carpet will remain on the extended rod of the piston. When the piston is retracted, the carpet breaks while the piston is retracting. This should not happen, because there is a block under the carpet at all times.

This may sound like a duplicate of MC-17851, but it is actually a bit of a different scenario, so i decided to open a new issue for it.