Last time we were there (Feb ‘20)
Wow, that's an update! (sarcasm, sorry, but the sargassum condidions vary from week to week). My girlfriend and I went to Pearl's beach on Dec 27 and 30 (not stayed at the resort, I own a tiny house in Playa del Carmen and use to go that beach for nude sunbathe). There's no more the black barrier. Dec 27 water conditions were acceptable, but on Dec 30 it was very windy, so lot of grass was on the beach and water looked cloudy (we preferred don't enter into the sea).
It's good to clarify that the sargassum is the endemic of that part of the ocean, and not like last years', which invaded all the Quintana Roo coast.
Regards