Since the devs decided to include dialogue for villagers talking about the mundane stuff the player did the day before, it seems a little weird to me that they wouldn't also include similar dialogue for holidays, too. If villagers care enough to talk about the fossils the player dug up the previous day for the fiftieth time on a day-to-day basis, you'd think they would be just as excited to talk about what the player did on a special day. A line or two for each personality type for the major holidays would not be hard, and I think that would help at least a little with making the villagers feel more responsive and alive.
Yeah i noticed that the day after Festivale too, and it was kinda jarring, this time in particular since they literally dance and partied all day and night, like i think it's the only time i've seen them party until 5 am not even going to sleep (do they do that for other holidays? i'm not sure). Especially because i had turned my island into a gawdy flaming disco with tons of rainbow Festivale decorations/floats/confetti machines blasting. It was like a hangover when i woke up on my island the next morning, and the first thing Kid Cat tells me about is how he has named his abs for like literally the 500th time.