I suspect this is related to other count conflict issues. There are apparently algorithmic differences. See also:
https://forum.inaturalist.org/t/significant-discrepancy-between-species-count-in-app-vs-desktop/2883
https://forum.inaturalist.org/t/a-bug-in-the-species-count/2417
My apologies that this does not directly answer this specific discrepancy, but I suspect that the comments in those threads are applicable here too. I have not seen any authoritative explanation for the differences, but this seems to be a known issue.