I conceded a game in practice mode (note: I’d still consider it a bug if I straight up lost) because I had enough data on the deck and wanted to make a change right away.
It seems that interrupted my winstreak (or… I guess it’s possible that changing from bronze to silver interrupted the winstreak?).
I have zero ranked matches lost for 20 games in a row and I only have a 15 match winstreak and the only loos was that one practice game.
I would expect practice games (because, hey, practice, against AI) not to ruin winstreaks.