It is strange to see that much discoloration above the water line. If the spa is raised then you could be getting seepage if the exterior was not sealed before placing the stone veneer.

Is seepage serious and can it be fixed ? If it can be fixed , does anyone know what the process is . My concern is our Pb may say that seepage is typical and normal in all spas . Posted another pic this was take 1 st thing in the morning before any use whatsoever of the pool

I would shut everything down for a couple days to see if the area dries out. It is remotely possible that you might be getting water moving from the spillway to the corner. You can also check the spa water level to see if it goes down at the same time. Also check the inside corner of the spa for missing grout at the tile line that might allow water to pass.
At worst removing that piece of stone is not a big deal if it helps identify the source of the leak.