If you spoke to Eververse and chose the big middle flashy rectangle 4 times, that'd do it. You only get one free one a week and only if you complete a bounty, first, but it still flashes like it's 'hey, I'm new, you can pick me up now' even if you don't have a free one available. So, you say you didn't buy anything, but sadly, the fact is that bright dust doesn't just disappear in a puff of dismantling smoke. It's a currency and not something that you can get rid of without spending it.