I noted that pretty much all of TUIs programmes across Europe are arriving with flight codes ending in P which are classed as positioning flights only.
Perhaps the Greeks have enforced this as reports of people sleeping on sunloungers as no rooms available. Remember the local population will be displaced as well.
I would be worried if RYR pax, they are only obliged to get you from A to B, not their problem if you have booked accommodation via third party.