MC 1.15.2
RM 2.3.0

1. Enter world
2. Remove a significant amount of blocks (probably one-by-one, not with a single command), thereby literally shining light on new blocks
3. Exit world
4. Open replay
5. Jump to the end
6. Jump back a bit (thereby skipping over the block removal without rendering even a single frame)
7. Lighting was not properly updated, newly exposed blocks should now be in shade