A while ago, I noticed some very small oscillations in my Cloudflare R2 bill (1-2 cents / month) and decided to ask about it out of curiosity. Support was tepid - understandable for my $1 / month account - and it wasn't until later that I realized the difference probably had to do with the number of days in the month.

Would this API have helped?

seems like you fit the profile of the dude who uncovered a major fraud just due to his habit of checking minor increases/expenses