So in practice at Snetterton 200 I bumped tyres with another car and this happened...
...and then cars started stopping all around the track, some in the pit lane, some on the grass, some mid corner....
....and then I finished the race, it errored out and I got this when I restarted.
View attachment 380027
Thankfully a quick overwrite from the cloud storage fixed it.
When my game crashed, that's the exact message I got. Not being a ps+ member, you can imagine my anger at the time lol. I back up to my external drive each time I exit the game now lol.
I also had a similar bug to your AI parking one. I did a 5 lap race at Sarthe, multi class GT, using the group 5 Capri. I was running 5th (was fighting hard with gt3 cars, but not able to keep up with the leading Zonda R, who was miles ahead), when on lap 3, AI cars started hitting the brakes in the middle of the mulsanne straight, one of them right in front of me when I was doing 280kph!
Luckily I avoided him, but I noticed the other cars ahead slowed at random too. They didn't do it all at the same time either. First the guy right in front did (first that I noticed anyway), and then I noticed a few cars dropping off the back of me, then I caught up with cars ahead very easily. They didn't completely stop like in yours, but slowed down to 80kph, like they had a pit limiter on. One even did it for a while, then sped back up as I was catching him (I was in 3rd at the time), then a lap later he did it again and stayed at 80, handing 2nd to me.
I had an engine issue near the end of lap 4, (from running too much boost in quali, thinking it'd let me turn it down for the race, but it just went straight to grid) so I pitted, and noticed a few AI cars in the pits, one of them left the pits in front of me, and never went over 80 after he got back on track lol.
I was 30 seconds behind the leading Zonda when I pitted, and 40 seconds ahead of the next car, and half way around the last lap I noticed I was bearing down on the Zonda, so he was the last car to give up on the race lol. I caught up to a massive pack of AIs on the last lap while leading, and they were overtaking each other and all running in a big pack at around 80 lol, so I carefully lapped them and finished the race. It was the strangest thing I've seen in a long time lol.
Also had an odd collision in practice. Very lightly tapped the rear of a car I was following, and my car stopped on the spot, with a strange bounce into the air, and my tyres and brakes went dead cold at the same time lol.