[Terr_]

AFAICT there is no scientific evidence of people actually getting vitamin-D deficiency from sunscreen use.

Even with really powerful sunscreen, every second you're exposed some portion of those UV-B wavelengths are still getting through to catalyze the production of Vitamin D.

According to one study [0] on a sunny summer day in Spain you could have 25% of your skin exposed and only need 7 minutes for that day's vitamin-D needs. (Obviously longer in dimmer conditions and wintertime, but those aren't the times people are going to slather sunscreen everywhere either.)

[0] https://pubmed.ncbi.nlm.nih.gov/29156273/

[TedDoesntTalk]

Note: vitamin D production is reduced with age (given same amount of sunlight exposure)

[InSteady]

Alcohol also interferes with vitamin D synthesis.