Vanilla dungeon spawners will spawn mobs based on the mob's spawn rules, for example if it's a skeleton, zombie spawner etc. it will spawn them if the block light level is 0, and if it's a blaze spawner it will spawn them if the block light level is less than 12. Spawners in RS dungeons don't seem to have the same rules, as they spawn mobs such as zombies and skeletons even above block light level 0. This is reproducible with only Repurposed Structures installed:

[✔] fabric-api-0.116.4+1.21.1
[✔] midnightlib-1.7.5-fabric+1.21.1
[✔] repurposed_structures-7.5.16+1.21.1-fabric

1. Load into a world and find a vanilla dungeon
2. Place a torch on the spawner and kill all mobs
3. Mobs will not spawn while the torch is placed. Removing the torch makes the mobs spawn again
4. Go to any RS dungeon, for example deepslate variant
5. Do the same thing as above and mobs will still spawn even with the torch on the spawner

Game log: https://mclo.gs/SUt1tUK

EDIT: Found out that processor lists set a valid block light level of 0 to 7 for spawners in almost all overworld structures, eg.

, removing that entry makes the spawners behave like vanilla spawners. Probably worth doing a pass on these files.

I will keep the ocean dungeons with the light level because they can spawn on ocean floor exposed to sky. The others, I'll remove the limits on.

Jungle fortress will keep limit since spawner is basically out in the open. Actually, I will just remove limits for most dungeons and mineshaft spawners but keep it for other structures since they can be near light or exposed, etc. Or maybe include mansions. Will need to look at the structures and make sure