A shower that leaks into the structure usually shows up somewhere other than the shower. The first signs are commonly in an adjoining room or the level below: a skirting board lifting, paint bubbling on the other side of the wall, a section of floor that stays damp, or a musty smell that does not clear.
There are several possible sources and they need different repairs, which is why identifying which one is involved matters more than acting quickly.
The waste connection can leak below floor level, where nothing is visible. Failed sealant at the wall to floor junction lets water behind the surface. Cracked grout or tiles admit water that the waterproofing membrane beneath should then contain, so whether it becomes a problem depends on the condition of that membrane. A failed membrane is the most involved case, because it usually means the recess has to be rebuilt.
The reason this is worth investigating rather than resealing hopefully is that resealing a surface does nothing if the water is entering below it, and the damage continues out of sight in the meantime.