The lighting of the "Client" doesn't correspond to that of the "Server"

In version 20w21a I was using a "datapack" to generate a dungeon system for a minigame.

When updating the world to 20w22a, I found that on certain occasions the generated structures have an incorrect lighting between "Server and Client".

(The map can be downloaded and to activate the generation, there is a command block with a lever on it.)