This is a PS4 question for me, but I'm thinking it might be a general thing. A few different times in the past month or so, I was in a practice or qualifying session and would get the "current lap invalidated" message as if I ran off course even though I was only touching curb (or maybe not even touching curb!)
At that time I figured maybe lag had something to do with it, where even if my connection is good, the hosts is bad. So in the same way that you might see someone with bad lag skittering about fore/aft/side to side, I might have been doing that same thing to whatever server was doling out penalties. And this lag doppleganger got me the penalty. Wouldn't take a big jump if the server was set to 0 tires out.
I've never seen or heard this discussed about AC, or any racing game. Curious if it's been brought up before.