While those reports came from expericing bugs in the Timewalking difficulty, there is no reason to think they don’t affect the normal or heroic modes as well.
• The red drake vehicles in the Grim Batol dungeon are bugged.
Normally, players would use them to fly above the dungeon and kill or weaken enemy packs, but they simply don’t fly and stay on the ground. Without this, the dungeon takes a substancial longer amount of time to finish.
A player that unknowingly click on drakes become stuck and can’t leave the vehicles without manually leaving the dungeon (which adds to the frustration and extra walking back time).
• The skill Disorienting Roar from the Grim Batol dungeon boss Forgemaster Throngus is bugged. Despite what the tooltip says, the debuff applied by the skill isn’t removed and provides an imense and constant haste reduction.
• At the start of the Mirmiron boss counter in the Ulduar raid, Leviathan Mk II attacks before he becomes targetable or interactable. This means he will likely always kill a random player before tanks can taunt or create aggro.
• [Edit.1] On the dungeon, Ahn’kahet: The Old Kingdom, the casted spell Embrace of the Vampyr from the boss Prince Taldaram is bugged and never breaks from damage. Since the affected player can’t receive healing, it always kills a player without counter-play.
This might be due to the way the casted spell was programmed. It seems to required a flat amount of damage to break, a number which most likely became unreachable due to the many changes and squishes made since the boss was introduced.