Why am I playing against Plat 3/4 players and yet Bronze 4?

Just to preface, the highest I've -ever- gotten was Diamond 4 on my main account back in 2016 as a 1 trick Nami player. I blew through Silver>Gold>Plat in a matter of 3 days, at that time. However, I did finally plateau at low Diamond and that was as high as I could get. I also played my boyfriend's account and got him to Diamond 5 as well, not because he couldn't do it, but because the season was ending soon and he was always busy with work and didn't have the time. (I'm happy to say he earned -himself- this season and is the reason I returned).

In my experience, you could definitely make a distinction of the differences between Silver>Gold>Plat players. After a 2 year hiatus, things are completely different.

Ignoring the previous Gold achieves on this account as I only played <20 ranked games randomly with friends those seasons. This account was strictly for only ARAM (which is no longer a thing since I've returned). I decided since I wanted to make this my new main account to try and get to Diamond again on this account.

After placements with 6W/2L, I got placed into Iron (while playing against Plat/Gold players) then placed into Bronze 4 (still against Plat 3/4 players)

I skipped divisions into to Bronze 2 after winning a few games. But even if I get into another win streak, I'll still only be moved up into Silver..then Gold..THEN Plat.

Being as _objective _ and _honest _ as I can be, I believe my skills and play style AT MY BEST average out at around High Plat/Low Diamond (right now is obv not my best because of a 2 yr hiatus from the game). That's the best, that I feel, I can play.

At this rate, if I continue at this rate of +32 LP per win / -10 per loss, I'm guessing I'll be playing against Diamond 5 players by the time I reach Gold... And, as I've said before, I feel that my best is at around that level which means I'll plateau around Gold (maybe even Silver)...

From what I've read online it's not possible to jump tiers, only divisions. How will it -ever- be possible to get out of the lower tiers (Bronze/Silv/Gold) if I perform at the level of a mid/high Plat player and yet I've been playing against Plat 3/4 since Bronze 4?

Is anyone else experiencing something like this? I'm curious as to other people's thoughts with this new system!