Nice shot. You are probably right, the twobanded anemonefish is known to inhabit these anemones in the Red Sea: Entacmaea quadricolor, Heteractis aurora, Heteractis crispa, Heteractis magnifica, and Stichodactyla gigantea

It isn't H. aurora or Stichodactyla gigantea, but the other 3 options are quite variable - even Entacmaea quadricolor sometimes looks like this(without bulbous tentacles). It looks like your anemone has bleached which is quite common in anemones - we used to see it every summer in Fiji where the bright red anemones (Heteractis magnifica) would go pale pink for a few months, then return to their full red colour when the water cooled down.