During my match against a Teferi player, I managed to get him to draw his last card which then prompted, "character has no cards left" during my phase. Once I ended my turn, instead of Teferi losing since he can't draw a card. Teferi was able to play their turn, which prompted me in losing the match. MTG has always made the player lose when they reach waterfall, why not here?

I don't have an option to see my match history, so I was unable to screenshot any supporting evidence, I can start by saying the account was chinese letters. I believe this was my first Teferi encounter.