The bug

Dungeons do not use cave_air, but normal air instead.

Note: Similar to MC-125112, dungeons exposed to the surface should use air.

How to reproduce

1. Create a world with the following seed

   -9144014475768710727
   

2. Teleport to a dungeon

   /teleport -153.64 24.00 44.63
   

3. Test for cave_air

   /execute if block ~ ~ ~ cave_air run say Found cave_air
   

   → The say command is not executed because no cave_air is found