So I have only been playing PC for 4 weekends, but have seen this at least 3 times:
(Example from today) I am P5 and following P4. P4 car graphics look a bit odd (glitchy, blocky (no fine detail) and for moments they are semi-transparent) and car movement is very twitchy.
P4 spins off track, I pass and my details show I am P4 for a second and then....said car reappears centre track a hundred metres ahead and I am P5 again.
Same thing happens repeatedly during the race. This car has huge offs into armco, gravel etc, sometimes can be seen piroueting up the track in front of me, then disappears for a moment and then resets to centre track, sometimes bouncing from armco to armco (each side of track) and teleports to centre track ahead.
In the example above, this other 'player' took me off the track and ended my race (on only lap 3). Yet another (another) example of 30 mins of practice and qualifying (and my life) wasted in this garbage game.