It depends. Yes sometimes it does indeed play like a really expert player. Something triggers it and yes once that happens it is very difficult to beat and if the RNG isn't with you impossible.
I don't know what causes the switch. But having played hundreds of ToT games in the last month I can say it does happen fairly frequently.
as far as i can tell novice still make very poor decisions
they seem like they do better because if hlaalu is in play, they sacrifice every card to it which builds up prestige, which i usually counter with rahjin spam (because they never destroy bewilderments and the -prestige)
the very few times i lost to npcs is usually because i wasnt getting enough rahjin cards to slow down their prestige gains
other decks that have a lot of card destroying like the reach deck can still cause the npc to destroy every card they own
the npcs also make poor decisions by spamming power patrons like druid king, reach, pelin so if they only have some power cards they gain prestige very slowly because they prioritize killing agents and using power on patrons
i have my main house (grand topal hideaway) listed in the housing tours, it has multiple target dummies, scribing altar, and grandmaster stations (in progress being filled out), as well as almost every antiquity furnishing on display to preview them
As of the update today, the novice now strongly resembles the one from before the adjustment. Using all the patron, repeatedly, buying the best cards, going for a patron win. Why on earth can't they just leave the frigging novice alone is beyond me. It's *supposed* to be easy!