What the Print is Doing Inside the Fabric
Heat and pressure push the ink and adhesive down between the threads, where they set as the garment cools. The print becomes part of the weave, which is why it stretches with the fabric and keeps its edges through a wash.
Heat is the one thing that can undo that bond. A hot wash softens the adhesive while the drum is agitating, and that combination is what lifts edges over time. Cold water on a normal cycle leaves it alone.