Riot please help I think this game is retarded

So here I am taking my placement matches for flex ok i get placed in bronze 1 for 6/3 wins and quickly get into silver. Then in solo/duo I get 9/10 wins and get placed in bronze 4. Like seriously carried almost all my games and had 100% winrate on zed and I get placed in bronze 4 when in flex when I did way worse I get placed in bronze 1. Can anyone explain this?