Mulligan Bug That Shows Final Hand

When both of us mulligan, then I mulligan again but my opponent gets a legal hand, I'm shown my opponent's hand.

I'm not sure if I should see their mulligan hand, but both times this happened to me I saw an Arceus V the first time, and a Comfey the second, both basic Pokémon that my opponent then played as their Active Pokémon and the rest of the cards that appeared seemed to be in line with what they played for their turn.