The photograph shows a typical case of a breakage that occurred when the tile was laid.
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As you can see the “crack” starts from the intersection of the two cuts made presumably with a diamond disk in order to create the recess for the wall.
These cracks normally form when tiles are weakened
as a result of cuts , partial or multiple, especially where corners or edges are formed.
Technically, these points ,interrupting the continuity of the material, become the most fragile and delicate points of the tile.
Unfortunately, cracks do not arise during cutting or immediately after , but rather when the tile is already laid and is subjected to different loads such as people’s footsteps, accidental impacts, weights from furniture and equipment, or stresses from the natural settling movement of the house.
There is a simple but ingenious technical expedient to be taken at the cutting stage to avoid this kind of problem.
The position of the vertex of the corner is identified and a hole is drilled at the corner with a small-diameter diamond cutter( 6 / 8 mm), and only then are the two cuts made with a specific diamond disc, taking care to leave the radius created by the cutter intact.
It is precisely this radius that gives greater strength to the tile, reducing the risk of cracking when the tile is laid by up to 90 percent.