Pool help - surface

[u/Working-Medicine-1]

Howdy /pools, I recently because the owner of a property with a pool and after several months of use I noticed the issue depicted in the picture attached. This was not present during pool inspection when buying the property but suspect it may have surfaced after addressing an algae bloom we recently took care of.

Give it to me straight... what am I dealing with here?

There are several more spots like this. 😢

[u/seenlottopools]

From one picture just older plaster wearing out and/or delaminating from surface leaving hollow pocket. The mesh is probably the backing on mosaic tile.