It’s a multi factor bug where you need DLC content that may or may not have been released to testers.
Most QA sticks with simple one-variable or very common two-variable scenarios or you get a combinatorial explosion that means it’s too expensive. Games make it even more complicated because they’re emergent and non-deterministic (for human testing) so there are a bazillion ways things could go.
In this particular case, nobody probably thought to test a long enough game session with a DLC skin on because why would a skin cause an issue other than rendering? Maybe it’s not even the skin, maybe it’s the deluxe edition bundle somehow and the skin just correlates. You don’t usually test with a bundle.
So yeah, it’s annoying, but speaking as an industry pro, I’d congratulate whoever found that bug, not penalize whoever didn’t.