I think that may be another issue we have been tracking:
I had also experienced it briefly, but then I stopped seeing it at the time. Recently I have begun another round of learning new cards, and this time on a deck that has multiple siblings per note. For the last several days, every time I finish studying a certain deck on iPad (AnkiMobile 2.0.83), the Decks screen shows more cards for the deck. If I sync and then open that deck again, roughly half of those cards remaining are available to study. I can go through about four rounds of finishing the deck and then getting more cards. All the cards that are added seem to be cards in the learning cue. I have bury new siblings until next day turned off, and bury review siblings turned on. I am not sure how learning siblings fit into that. I think I would prefer learning cards to not be buried.
Anyway, if I am not mistaken, AnkiMobile does not yet have any of the fixes of the desktop beta 2.1.50 incorporated, so I would therefore expect counts between desktop beta and iOS release to be inconsistent.