That ledge looks terrible. The PB should be ashamed of that and make it right - complete chip out and replaster. At a minimum, the ledge should be completely redone, no patches.
I would also have a very frank discussion with the PB about implementing a closing strategy that does NOT drain that ledge. I realize that they are concerned about a complete freeze of water all the way down but that is an extreme in my opinion. Even in freezing environments, if that water was properly covered AND something was done to add agitation (perhaps a submersible pump), water will take a long time to freeze and would not likely freeze completely. Draining a ledge and leaving it exposed to rapidly fluctuating air temperatures when it is sitting millimeters away from a body of water that is only changing its temp slowly is a recipe for continued freeze-thaw damage.
Just sayin’ ....