I am kind of on same opinion , plus the fact that Dan got hurt while doing it and was tired/sleeping when he can, which probably hindered his sessions , like when they stopped because his hand bleed. Also for me Dan had to wait before giving the gift, he knew himself it wasn't the best time , to give it while he was having headache and was already annoyed from all the gifts that was delivered. And what i think is Jaekyung probably build a solid wall around him to don't let others to close , since all his previous "partners" was with him probably just for the money.
100%
Okay, so from what I seeing now is that when his drunk his true feelings show but when his sober he would burry all of it as for why he got angry I mean it kinda make sense, think about his doing a side job and gets super tired and as twisted as the seme is he was probably worried about him but further more he was probably angry because he knows that Dan doesn't have a lot of money and he has hospital bills to pay etc so he was most likely thinking that all his money will go that and got mad that he got an expensive gift. Honestly I would be mad as will if someone I know was going through a tough time and they decided to buy me an expensive gift for my birthday, I honestly would rather they save that money and get me something they can afford it still will hold same meaning. So in this case I don't really see as a red flag nor do I see it as a green flag either his reaction kinda board lines morally grey.