As a full-stack/generalist product designer, I’ve watched the industry's obsession with titles for many years. Sure, we can keep being snarky about it, and continue throwing around funny tweets, but when did this help anyone?
UI is a subset of UX. Both terms have different meanings and, whenever possible, should not be used interchangeably. The title “UX/UI designer” makes little sense in terms of semantics. Every UI designer is a UX designer by definition, and being a UX designer without a more specific field of work is quite rare. Talking about “UX” without specifics can quickly render any conversation meaningless.