We experienced BUG with lights, but maybe it is not related only to 1.18.02 (we start playing this game with release 1.18, and noticed this problem in 1.18.01 for first time).
We are playing on private MP server 1.18.02, now 1.18.03), 5 people (different computers), and we all are experiencing the same problem with light sources in caves.
Those light sources are emitting light only when held in hand or in quick menu positions and even then the light effects is only local (light circle around local player), another player with light in hand/quick menu) is not emitting lights for other players. Furthermore, when lights are placed somewhere (ground, walls, etc.), they stop emitting any lights for anyone (nor local), and room/cave is totally black for everyone.
I can provide SAVE game if needed with coordinates.
Note:
This seems to be related to some places, because in other part of cave it seems to be working fine.
We experienced that also in other locations thousands blocks away.
Note2:
It seems that this starts happening, when placing more light sources in one area (chunk?).
Have anyone experienced something like this too? I will try to upload savegame with coordinates in 2 days.