Need help with stopping ghast spawns in my nether base

Built this without thinking about ghast and explosive resistance i have placed leaves flush with the ground with 4 blocks in between thinking this would stop ghast spawns since i thought they needed a 5 x 5 x 5 area to spawn but I am still getting ghast spawns in the dome anyone got any idea as to why? And what I could do to stop it I really don’t wanna lose all that work 1.20.4