the mob spawner spawns monster even if lit by torches, for example, I was going to the nether fortress when the blaze spawner spawn even while I was filling it with torches. I almost died from this bag, I hope it will help you to perfect the snapshots
after Minecraft 20w11a
-BIGC05010
Blazes can spawn in light level 11 and below and thus their spawners require more than just torches in order to be disabled. See https://minecraft.gamepedia.com/Spawner#Disabling.