Firstly, yeah... RDRO is utterly plauged with all sorts of cheaters using trainers and all kinds of cheats is full of crap, at least for PC.
The standard strategy you basically have to employ is that whenever you see something nonsense like that happen is you have to jump to another instance/lobby. Depending on your luck, you may have to do this every 15 to 60 minutes aaaand some cheats allow the cheater to follow you to your new lobby.
Secondly...
A few years back I was in RDRO and was attacked by a cheater.
I had a broke ass level 15ish character with the just a few of the least expensive guns.
They had infinite ammo. Teleport hopping. Spawned 10 additional NPCs versions of themselves, then of my character, then zombies, then legendary animals (basically fucking monsters).
All the while they're scrambling their name in the scoreboard every minute and create spoofs to make it harder to actually do a report or have the grievance system actually work correctly.
I killed them all. I died over and over again, but I kept killing them. Whittled down the fake names and spoofs and kept doing the grievance thing until it was actually landing on one consistent name.
Then the cheater began spawning gigantic props like boats attached to their character, which rotated and hit with physics force when they rotated, which they could shoot out of but I could not shoot into.
But uh, I managed to juke my way through cracks in the collision mesh, then shoot him.
He got tired of this at some point... and just turned himself invisible.
But, by this point I'd been killed enough times that I'd managed to get him showing up on my radar.
I'd by then long since run out of ammo... and began stalking him, via radar, with just a knife and lasso, sometimes the running tackle with the lasso that leads into a hogtie, other times actually managing to sneak up behind him, executing an invisible foe.
After an hour and a half of this, he started slipping up, and I could see him attempting to flee me, teleport half a klik away and just stand there for 30 seconds, then move a bit, then pause again, presumably fiddling around in his menus.
I killed him a few more times in this state, and he quit, he left.
... I would have just jumped to another instance if he had not killed my horse.
Do not fuck with a man's horse lol.
... anyway, yeah. hung up my hat after that. fucking nonsense.