Guild Wars 2

Why is it that thieves get a 60 second revealed debuff every single fight on tier 3 fights? Is this a bug or deliberate?

During the Ravenous stage you cannot stealth. I’m not sure about the rest of the fights, but I can tell you in all certainty that you do not need it. Lots of the thief’s utilities make the challenges a cake-walk. If you are using utils or wasting init to stealth, you are making things much harder on yourself and may have become a bit too dependent on it.