I got a mythic trinket from my vault.
Got the same mythic trinket from a nebulous voidcore (M+).
Reported, GM closed the ticket as resolved with some other thing about loot, nothing to do with what I reported.
not broken, moving forward won’t get that trinket from a bonus roll anymore. a bonus roll has every drop in the loot table and removes the ones that you get FROM using the Bonus Rolls not from other sources.