Almost looks like a full crack through the entire X and Y axis.

Cracks are typically from movement. Linear cracks sometimes occur over a seam that has differential movement across the seam.

Movement in a shower pan is not good.

Diagnosis prior to demo? Why is is moving? Any knowledge of the structure underneath, how the slope was created, materials used, etc, new house old house, etc.

Regardless, the only true repair for a failed shower pan is remove and replace. Remove is the easy part. Replacement includes integration of the new waterproofing with the existing, that can be the difficult part.

As long as its not leaking it indicates the membrane is still intact. But for a 4 month old shower, call the tiler if you hired him direct. Call the contractor if you had a builder who hired the subs himself. Just tell them "I might need a new shower, I'd like you to come out and take a look." lol

Thank you, MongoCT and Millworkman!

We have not noticed any leaks anywhere. This was a renovation of an older house where a bedroom was turned into a bathroom. They took everything down to the studs. I used a GC. I don't have any pictures of the shower pan "in progress." Here are some pictures of the area. The floor was used for a shower 8 hours prior to this picture.

So is the consensus that it is a failed shower pan? Could it be anything else?

"So is the consensus that it is a failed shower pan?"

Yes.

"Could it be anything else?"

Not likely.

"So is the consensus that it is a failed shower pan?"

Cracked grout typically telegraphs a failure of whatever is underneath. A weak mud bed that is too thin? A mud bed made with too much water, and the cracks are latent shrinkage cracks in the mud bed? A foam tray that was improperly installed? A subfloor with too much flex? A "preslope" made from shimmed plywood, improperly built? Cement board used as "the pan"?

It's cracked. Significantly. In both axis. And significant cracking is a failure, especially only a few months after the build.

If the crack is due to flexural movement underneath the tile, if it continues to have slight movement, the grout at the crack could powder away over time. Small crevices at the crack can hold sloughed off skin cells, soap residue, etc.

The good news? It appears to not be leaking. So it appears the membrane is still intact.

Definitely call your builder back to have a look.

Thank you so much, MongoCT and Millworkman. There are so many things to address at the end of a project and I've needed to triage the problem and concerns...getting. my ducks in a row, so to speak. I will circle back with more updates after we speak to him for the benefit of others. Thanks again!

What is the discoloration of the tile? Are the dark areas dampness 8 hours after a shower or is it staining? Were the floor and walls waterproofed before tiling and was the structure checked to see that it would support the extra weight of the shower pan/tile etc

Jeff, the tile is marble. The discoloration is because the marble is porous and absorbs water.

Why have some areas absorbed more water? Does it ever dry out and look the same color everywhere?