This issue has kind of been mentioned before. But it includes more than just hand size. I played Ancient Greenwarden while playing against a mill oppent and had tons of land in my graveyard. Because of this i couldn't play my commander, or any cards in my actual hand because it only showed the middle like 20 cards that were all lands i could play from graveyard. So if you play any decks thay give you massive ammounts of cards to play at once you are forced to play the middle section of cards and not the one card you might want to. This issue appears to be on all mobile not any specific system.