This bug happens in the editor on an unfinshed map with a CP taken in high speed(lowest speed it occured for me was CP taken at 468kmh). After re-saving, closing the editor and opening it again (game restart doesn't change anything), spawning in this CP with a test mode does't alllow the car to accelerate. Works again after rewriting of the respawn.
Video with the bug captured:
This isn't a new bug, I remember discovering it for the first time in 2021.
I can provide the map file but have no idea how.