Yes, all of those and more. Our measurement precision is much better than the year-to-year first and second derivatives of day length. https://datacenter.iers.org/singlePlot.php?plotname=Bulletin... has the most relevant plot to this; the vertical jumps reflect leap seconds. (IERS has other plots for other dimensions of rotation, but I like this one.)

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doctoboggan 2 hours ago | parent [-]

Very interesting, I wonder what happened in 2020 that causes the rotational speed to start drifting the other way?

Pandemic -> more people working from home -> less people in tall office buildings -> faster rotation (like a skater pulling in their arms).

Probably not remotely true but it would be funny.

	▲	wongarsu 2 hours ago \| parent [-]
		Seems like the seasonal change in June-October increased My best guess would be it's somehow related to water distribution? More water going into the atmosphere? Glaciers growing (unlikely)? Did multiple huge water reservoirs go into service and get filled up over the summer months?