To be very clear, your frame is broken, do not ride it, get a replacement, and don't pay for it. FYI, it's obvious with the video, but impossible to tell with the picture alone. For any kind of warranty question, i find that video is the way to go.
I guess it makes you question the whole "affordable chinese yet ultra light carbon frame" thing a bit... Yishun / Light carbon have excellent reputation, yet less than 5 frames of the LC17 on this forum, and one's cracked out of the box. Not the kind of failure rate we want to live with, and it's infinitely more serious than a shitty C ring causing headset play, flexy bars that can be swapped for 100$ or a slipping seat post we can shim with a piece of soda can or some fiberglass cloth.
That is really, really not good.
Well not trying to be devils advocate but let's also take this with a pinch of salt. Yes, this is broken, yes this should not happen, yes this could have serious consequences, and yes I'm sure he should ask and get a replacement, but this can happen with absolutely any company.
For me it's all about how companies deal with these cases which actually matter. Customer service/warranty is way more important than any issue reported. He spotted this yesterday, asked for opinion, he will contact the company (whichever it is). The answer from them is the actual key here.
I have worked already in quite a couple of bikes and for me it's always about transparency, communication and good support. That's how I assess the companies I chose to work with in my business.
So let's wait and see. Having just 4 or 5 or even 10 bikes of these in this forum means little. I am buying one or two LC bikes to test the service regardless of this report here. If I like their service I can propose the frame/brand to my clients as an option. If not I keep with my provider and keep testing others.