It's definitely genuine and has been widely reported on in GoT fan circles. There were signs things were going seriously off the rails on quality even before Season 8 with, for example:
(i) The Bravos scenes after Arya got stabbed by the Waif when Arya clearly should have died after swimming with severe stab wounds in what was probably effectively an open sewer,
(ii) the less than convincing way the Freys all got offed and Arya was able to escape in the aftermath,
(iii) Bronn's rescue of Jaime when the latter clearly should have drowned given his heavy armour,
(iv) and most importantly when Gendry ran back to the wall and a raven was sent to summon Danerys and the dragons, with both the ravens and the dragons needing to fly as fast as a jumbo jet for the story's timeline to make sense.
Most fans seemed to be oblivious to it and were still lapping it up. If more had complained maybe HBO would have told D&D that their writing wasn't up to snuff and that they needed to get GRRM more involved again.