No one knows what the "right" level is and where too much of a good thing becomes a problem. It almost certainly varies by individual genetics, and maybe by age, sex, and things we don't know about. Like how much K2 and magnesium we're also getting. I haven't seen anyone recommending vitamin D levels over 100ng.
https://www.grassrootshealth.net/project/our-scientists/
https://www.grassrootshealth.net/project/our-scientists/

