All custom nether dimension_type datapacks do not actually modify the nether in any way.
A custom datapack dimension_type the_nether.json containing:
{
"has_raids": false,
"logical_height": 128,
"infiniburn": "minecraft:infiniburn_nether",
"ambient_light": 0.1,
"piglin_safe": true,
"bed_works": false,
"respawn_anchor_works": true,
"ultrawarm": true,
"natural": false,
"coordinate_scale": 8.0,
"fixed_time": 18000,
"has_skylight": false,
"has_ceiling": false //was true
}{
"has_raids": false,
"logical_height": 128,
"infiniburn": "minecraft:infiniburn_nether",
"ambient_light": 0.1,
"piglin_safe": true,
"bed_works": false,
"respawn_anchor_works": true,
"ultrawarm": true,
"natural": false,
"coordinate_scale": 8.0,
"fixed_time": 18000,
"has_skylight": false,
"has_ceiling": false //was true
}Intended mechanic:
Would remove the nether roof
Please attach the entire data pack