propeller tail, barraskewda's ability is said to ignore other pokemons abilities. However, it seems to be not ignoring sturdy.
https://play.pokemonshowdown.com/battle-gen8oubeta-1011124878
Not a bug. It ignores abilities and moves that draw in moves. This list includes abilities like Storm Drain and Lightningrod, its not supposed to function like a Mold Breaker.
Choice item equiped dinamaxes sometimes ignore the choice lock, and sometimes it is transfered to the boosted moves, either they should always lose lock after dinamaxing or never, any which way, it's a bug.
Not a bug. In fact, it is an in-game mechanic. Under Dynamax, Choice items are completely nullified. You are not locked to a move, and you can't benefit from the stat boost. Once the Dynamax is over you will be locked to the move you used before dynamaxing. I put up a replay for you to test yourself and see.
https://replay.pokemonshowdown.com/gen8oubeta-1011113952
Cinderace taking no SR damage from turn 29-30 till the end of the game.
Heavy Duty Boots is an item that negates hazard damage, not a bug.