How accurate is ACPL?

I just looked at my chess insights to see my average centipawn loss. For some reason, my bullet and ultrabullet have nearly identical (71 vs 70.2) values, as well as my blitz and classical (47.9 vs 45.8).

I find it very hard to believe this is accurate. My ultrabullet should be far worse than my bullet, since every game I sac multiple pieces and play terribly, while I play at least ok in bullet. And my play in classical games is also significantly better than in blitz (which may be why I'm 200 points higher in classical than blitz). So why are the ACPL values the same?

I was also confused at first seeing my ACPL. I think the ACPL is calculated only for those games for which computer analysis has been performed. Because without computer analysis, I don't think ACPL can be calculated. Now in ultrabullet and blitz games, you would have analyzed only certain games in which you played well. This explains the reason for your ACPL being equal for your ultrabullet and bulet games as well as blitz and classical games.