The animation thing happens late into a run when you sell something and get coins flying in. When that happens, if you have enough lag, the coins can start to orbit around for a while until collected, or they become part of the circle of doom (which is just a ring of coins orbiting in the middle of the inventory), which led to my game requiring a restart every time it happened, as they don't get removed upon clearing/leaving a run. (I don't know the exact trigger for it, but if you were to run a particularly strong build into the late game and sell some items, you can probably encounter it)