hi lovely! you're not the first person who's asked something similar to this, so looking back I perhaps wonder if I should've made it a bit clearer.
the reason y/n was angry is because she'd given him a huge level of trust and privilege (being able to go into her new workshop without needed prior confirmation + knowing where her new address was), and he walks into a meeting between y/n and hoseok and rather than waiting for them to finish interacting properly, he asserts himself in a way that he shouldn't, even though he knows both of them. in the past when he's been at the workshop he's been silent in the background when y/n interacts with other customers, so it's more obvious that he's doing it for A Reason.
the way he treats hoseok like dirt is a bit more nuanced, hm. in the underworld in this story, a lot of people go by a pseudonym/moniker, so revealing someone's true name without their consent goes against the implicit "code" they have. especially in this instance as yoongi is incredibly taciturn and never reveals his hand, or his emotions, or how he thinks/feels/who he knows, so it's quite a big deal. he interrupts their conversation by revealing he knows Hoseok personally, and that he's close enough to know the Hope Broker's real name, so it's twofold.
(and then when y/n asks him why he did that, rather than apologise or explain or whatever else, yoongi butts heads with her, which is what riles her up even more. so yeah! that's why.)
I hope that makes sense! reading back now I realise I could have expounded on it a bit and that y/n's reaction seems a bit OTT if the context isn't clear, as a lot of it is implicit but I didn't take the time to explain that implicit nature as much as I could have 💕
