I have no idea what the cause of this is. Usually this x2 speed thing happens after spawning in a vehicle, only lasts one second. This time it lasted until I closed the game. Random videos for your own enjoyment. I would post this as a bug report but I have no idea what causes this. AI driver crashing because it doesn't know what to do in x2 speed at the dragstrip: Apparently x2 speed ignores slow motion aswell.
I’ve noticed this issue as well. For me, it occurs if I go to another map after using the thumbnail generator on the showroom map.
This is exactly what happened. I used the showroom map and thumbnail generator just before, but I didn't think much of it.