I just had this happen to me playing Tasha, I think its bugged. My opponent didn't attack Tasha or myself one turn and attacked a second plainswalker so Tasha's -1/-1 counters didn't trigger. However when it passed to my turn the ability didn't go away, despite the ability stating "Until your next turn" and it proceeded to stack with the +1 from that turn.
I managed to do it again the next couple turns as the opponent didn't attack and it allowed the Tasha +1s to stack over the 2 turns.
Attached is a log from the game (I think) I had detailed logs enabled so if this isn't the correct one I would be glad to find the correct one. However a ctrl+f found the player name of my opponent in the file so I think it is correct.
I just had this happen to me playing Tasha, I think its bugged. My opponent didn't attack Tasha or myself one turn and attacked a second plainswalker so Tasha's -1/-1 counters didn't trigger. However when it passed to my turn the ability didn't go away, despite the ability stating "Until your next turn" and it proceeded to stack with the +1 from that turn.
I managed to do it again the next couple turns as the opponent didn't attack and it allowed the Tasha +1s to stack over the 2 turns.
Attached is a log from the game (I think) I had detailed logs enabled so if this isn't the correct one I would be glad to find the correct one. However a ctrl+f found the player name of my opponent in the file so I think it is correct.