I don't understand flex que

So I got on league to see if they finally added ranked ques back and all behold, flex que is up. So I started playing, first game I was the only gold. I won and I was like 15-3-10. The next game and every single other game I'm matched with plats and diamonds. I win 5 games and yet I get bronze 4. How is this system even balanced. Also will this affect my soloq rank? I've been gold for the past 3 years and I really don't want to have a hard reset and get placed in like bronze 2.