There is one medium sized almost randomized trial that shows a strong result. I'm not interested in small retrospective studies. There are 50 retrospective studies that show HCQ is an amazing drug against covid.

Clearly since there is little downside to given vitamin D to people who have low levels, it can and probably should be done, but that is very far from proving that it is a "potent inhibitor" of covid. There also is a clear bias for the person who makes that site since they also want it to be true. Maybe they don't look as hard for studies which disprove what they want. It isn't an overwhelming case.

There is more than enough evidence for a big RCT to actually confirm, but given the safety considerations and low expense it probably makes more sense to just dose everybody and hope it works. But I don't see how you could make grand claims with this evidence.