That seems like the most plausible reason.
Tiling over old tiles isn’t that uncommon, and here I suspect they used very little glue (or poor quality glue) so as to not increase the thickness of the floor too much (to avoid issues with thresholds etc.). Thin and/or low quality tiles could be another explanation, as to why they crack lack this…
Either way, I can’t think of a way to fix this without ripping up the old tiles and laying new ones.
If people could just be kind and turn off the server when they leave.
If you close a tab, get a prompt; “it looks like you’re leaving this website, would you like to power down the server(s)?”