I just want to add that I play on a server with large biomes enabled so please don’t release the final update before fixing this issue because it would create weird chunk borders.
A lot of things behave weirdly when there is server lag, not just fireworks.
To fix this they would need to fix the lag itself which is the cause of the problem.
Also when you open shulker boxes... I really doubt piglins use shulker boxes... They should find a way to make it so it only happens to chests with a special tag that were "placed" by the piglins.
Hey, the reason why I believe it is a bug is because mobs cannot spawn on blocks that have redstone components such as buttons, levers, etc occupying the same block. And doors/trapdoors are in the redstone category of the creative inventory, so logically it should apply for them as well.