I think 울쟈긔 translates to like my dear my darling and 우리 자기 translates to our darling our baby? I do know that 우리 is ours and 자기can mean darling/honey but it can also mean oneself but i don't think it means oneself in this context.
Ah yes, thank you! This is also the translation/interpretation that I think is most appropriate for 울쟈긔. Some ATINYs on Twitter have also translated it in a similar way.
Though I have to say, calling a really close friend 자기(야) as an endearment is not unheard of. Wooyoung does that to Serim, Yeonjun, Changbin too if I remember it correctly, and some ATEEZ members like San. It just threw me off (/pos) that Mingi (and totally not KQ editors) used 울쟈긔 as a nickname for Yunho 😀 Doesn't mean they have anything inherently romantic going on but I'm too yungi pilled to be sane about this.
