Oof, catastrophic failure. You’re going to find very thin material without adequate backing and a honeycomb support pattern underneath, not some kind of mosaic or whatever you’re imagining. Every one of these tiles is failing and those cracks are exposing their structural shape. The mortar bed below is probably too chintzy and the tiles were not properly bedded to infill the cavity voids. I’m no tile guy. Just a designer who grew up in the trades as a cabinetmaker.