I have expressed this bug multiple times but it has never received any attention. the spawning mechanics of mobs in the nether work perfectly fine if the nether is only visited for excursions however as i have expanded my base i am encountering more and more spawning bugs that allow ghasts and pig men to spawn directly inside well lit player built structures within close proximity to the player. in order for nether settlements to function properly there needs to be a change to mob spawning rules that prevent mobs from spawning in areas that for all intents and purposes a mob should not be able to enter be it due to walls doors or a combination of defenses. bugs that let mobs spawn inside fortified areas defeat the entire purpose of building fortresses and other fortified settlements.

the simplest solution would be to blacklist non native nether blocks eg mobs cannot spawn on anything except netherrak netherbrick soulsand or lava. this would allow mobs to continually spawn regardless of light level but would prevent them from appearing in secure structures.