Stats get increasingly expensive and useless to store, but one would think mDAU would be one tagged for high precision long retention storage.
However, saving user identifiable information > 90d is a challenge these days - you have to anonymize it, which defeats Musk's purported goal. (And it might be illegal to share that data w/ a 3rd party.)
Heck, not only “what happens on Twitter each day of the week” is a very valid data question, but even by the hour.