The most surprising cozy game trend this year was the desktop pet renaissance
Back in February I declared that desktop pets are so back, and then partial-screen idler games (pets and otherwise) wound up being so much more back this year than I had predicted. In a year of increasingly experimental cozy games, they were one of the most identifiable and quintessentially cozy trends.
Subgenre trends happen all over gaming (the battle royale to extraction shooter pipeline, for instance) and cozy games are no exception. For a few years after Stardew Valley, absolutely everyone was making a farm sim.