I've noticed the game occasionally starts running in slow motion. it still registers me running around, fighting, collecting resources etc. but the entire game is running at a greatly reduced speed making things feel very awkward.
This has occurred on multiple occasions (but I can't recall all of them off hand, will comment with updates if I see something else that triggers it), but I know it happens on some full moons.
Also relevant: the slowdown persisted for the entirety of the full moon, and disappeared seconds after it ended -- i.e. it almost immediately went back to normal game speed).
I attached a clip of this slowdown (you can skip the first bit of the clip where I am staring at my map) -- starts around the 10 second mark
Run around and be active as a full moon is triggered
(potentially relevant: I was playing as Wickerbottom and was insane at the time. was also Lush season at the time but I recall it happening earlier in this world too so I don't think it's season-specific.)