A global elite becomes shit when playing on esport platforms, but why?

RESUME:
I play official valve servers= Im jesus!
I play any other platform= Im shit!
But...why?

Am I the only one who experiences incredible but almost imperceptible lag when playing on Faceit or other esport platforms? I can't even play at 10% of my skill level because the game feels sluggish. In casual mode and in regular competitive or Premier modes, I'm incredibly good. I have very fast reaction times, amazing aim, impressive movement and flicks, and I'd say that in 70% of matches I'm accused of using cheats, while in casual it's 100% of the matches. On my lucky days, I can honestly say that I could beat Donk or Zywoo in PvP at least a few rounds, maybe ending in a draw, but that's only on very rare days when my concentration on the game reaches almost religious levels.

Getting back to the topic, I've already reached the global elite rank in CS:GO and CS:2, it was incredibly difficult because the high ranks are full of cheaters, (I once won a match one tap killing a guy with ragebot 5 times! 13-10!). So I decided to try Faceit, and the experience was terrible. The gameplay just doesn't feel right, and I don't know what it is, but something is completely ruining my gameplay.

I've come to the conclusion that it's lag, but I think that's unlikely. I don't have any servers in my region but I usually have matches with 14 to 30 ping, which isn't bad at all. However, even when I'm playing on absurdly low levels I'm even embarrassed to admit I've been playing matches there; and I'm talking about Faceit 2, 3, 4... It's simply unplayable. It's like my bullets aren't going where they should, while the opponent's bullets are being guided right to my temple! I die behind walls, my enemies appear to be running and gunning but they land perfect headshots, I cant do a single strafe correctly or bhop, my movement becomes absolute shit, I die behind cover.
I go first, I die, I go last, I die, If I bait, I die, If I lurk I die...

In my subconscious, I think I can sense it's lag. The game doesnt look laggy, no shakes, no weird tp's, all ok, but when playing it feels like when cs2 was released for the first time, absolute shit. I think it's a few milliseconds between moving the mouse, pressing a key, and firing a shot, which prevents me from playing remotely well, or the explanation is more related to connection to the server, or how the data is managed, idk. I'm referring to the fact that on Faceit, and a bit on Gamers Club (I'm from SA), another platform in the region, I go from being Global Elite with 4k hours to Silver 4.

At least my knowledge of the game is extensive enough to still win an occasional match, provide good information, and predict movements against these silver 4, but the only kills I can get so far are by hiding in places where I find them, or when they're extremely distracted, or by attacking from behind.

You are free to criticize me, insult me, despise me, call me a noob, a "reality check" loser, and even wish me dead.
I'll be reading commnts, (pls tell me im not the only one.)