Adverse reaction reports describe suspected side effects. A report does not mean the drug caused the event — co-medications, underlying disease and coincidence all contribute.
Is Vitamin D3 cholecalciferol) approved in United States?
Yes. FDA has authorised it.
Who is the marketing authorisation holder for Vitamin D3 cholecalciferol) in United States?
Abramson Cancer Center at Penn Medicine is the originator. The local marketing authorisation holder may differ — check the official source linked above.