Why would there be any? It's not like you're focusing on something close to your eyes, the optics have the focal point quite far away so that you can look in the distance and read the screen at the same time.

VR glasses tend to focus around 1-2 metres away, but XR glasses a lot further. Not quite infinity but closer to infinity than VR glasses. Infinity is the most restful spot for the human eye. The glasses require less muscle tension (accommodation) looking at an AR display than looking at a monitor.

Usually the idea that it's bad is because people think it's bad to look at screens so close to the eye but optically they're not close at all. If they were you wouldn't be able to see anything unless you're incredibly nearsighted.

I'm also interested in this: (Display) Glass manufacturers are mostly in Chinese-based, tried to research but didn't get any decent results

My eye sight declined when I started using XR regularly. However it was also at the age where my eye sight was probably going to decline anyway!