Ever since Loading... started beign a nuissance for Harpies, players started to look for synergistic cards that could out this powerful Xyz Monster. Initially, Loading... felt like the call but recently we started seeing Level 4 Winged Beasts being used like Loading... or Loading... since you can tutor them with Loading... and also open them in conjuction with Loading... to have a starting play in other scenarios which is something that Harpie's Pet Dragon doesn't offer.
Harpies did what every other Tier 1 deck does whenever players start to find counters for it: adapt. Loading... and Loading... are new to the Harpie toolbox, as Glife is a normal summon that deals with a backrow while also being a Loading... target. More importantly, it's not a Harpie Lady, playing around Loading... . Harpie's Pet Dragon was experimented in the past, but it became more relevant now as it allows you to go into Loading... while never being at risk of Patriarch disruption. As the meta evolves, every deck adapts to its counters, and what Harpie has been doing recently is a prime example of it.
Onomat is still here as the second deck to beat in the format. It has Loading... to OTK, Loading... to control the board, or one-to-two Loading... s to make some nice Xyz Monsters and put pressure on the board. Nothing really changed for the deck, just the other decks trying to adapt to it since it entered the format and force people to respect cards like Loading... . That prompted a response from Harpies and as such they play either Loading... or Loading... in combination with Loading... or Loading... to play through it. The deck is not slowing down any time soon and is just going to remain in this format as a good deck overall. With that it stay at Tier 2