Is it a known thing to do worse than usual during placements, or is it just RNG / the way we played?

Is it coded in the algorithm or something that placements are more difficult / you get matched with lower ELO? Because I have about a 50% winrate in ranked (not initially but it balanced out near the end of the season). Probably 50-52%ish winrate. But the first placements I play I absloutely get demolished. Like it isn't even close. My team feeds, I feed, and overall it seems like the enemy is just much higher ELO.

Is it just luck or something? Because I guarantee after I get into Wood 6 with my placements I will end up with a 50% winrate in ranked.