An argument can be made that TOO much stuff is viable rn, making the metagame very matchup fishy. Answering all of Raging Bolt, Kyurem, Gouging, etc on the same team while not losing to other stuff like Gliscor, Arch Rain, or Deo-S is hard. But, I feel that has always been an issue and there is still room to play around these strategies, though perhaps less so against rain and sun.
Even dealing with hazard stack has room to be played around by exerting enough pressure to stop gliscor or whatever from setting up hazards in the first place.
Gen 9 I think is also highlighting the importance of "1 free turn" more than any other generation, which is exacerbated by Tera. Guessing incorrectly vs a threat like Valiant often can mean death even if you have it covered on paper. Tera lets Pokemon like these run far more viable sets in the past and makes it so there is a legit use case for niche options like Liquidation. That being said, Tera is also important in taking away that "1 free turn" by interrupting a mon in its sweep and the like + can pave the way for new defensive options in a match.
I'm not really making any sweeping statements here, just pointing out some observations lol.