Steps to reproduce:

1. Open the world provided here: https://drive.google.com/file/d/19l2j_xqDQReovve5hVJOE87Zq1V5F9UR/view?usp=drive_link
2. Place a redstone block at 1352 64 1657 to start the contraption.
3. Enter spectator mode and set your speed to the maximum.
4. Fly into the positive X/Z direction until you are at the stony shore/mountain.
5. Fly back to the machine.
6. Sometimes a lighting glitch is now visible where light is cut off at a chunk border.
7. If this did not happen, restart the machine if it has stopped and repeat the process.