losing promo's still promoted glitch

I wish I had proof of this sorry. So I was playing ranked yesterday and got into my promos while chat-restricted and got a free win. Today I played my 2 promo matches and lost both of them the second one was the last game of my chat restriction. When I left the game to the end-game results screen. It said congratualtions you have been promoted to bronze IV. I don't know what caused this or how to replicate it.