"Fix" for matchmaking

Main rank is s3. I played through my flex placements and won 7/10 and got placed s3 and was against platinums and diamonds. Fix comes out I win my first game to get rank again and get put in bronze 4. Bronze 4 is the same rank as my friend who only won 4 placements and then lost his last game which made him get placed again. I just dont understand how this is fair or makes sense.