It’s still backstory if it’s “for context.” Maybe better done as separate oneshots, or an episodic serial? Out-of-order is going to confuse the reader IMO, (and in my case, myself too.) This is especially true if there’s something where a character dies, and now you’re talking if they’re alive. Another slight exception here is when I’m doing multiple POVs, so I want to cover character “A” in a dedicated chapter, and “B” in the next (but, the events should be sufficiently disassociated/separate for that to make sense). To me, the strong “out-of-order” means there’s a structural issue to the story, maybe you’re starting in the wrong spot/incident? Hope I’m making sense here.