Personally, unless there are citations for specific studies on this topic, I'd treat that as personal preference, not something to be especially worried about. If we spent all our energy avoiding things that could possibly be harmful, or that someone we heard or read about told us to avoid, we'd have no time for anything else.
I seem to be wired to worry, so I make a particular effort to analyze which things are things I can:
a.) Know are of a large enough order of magnitude to really matter, and
b.) I can do something about
Keto fits the bill there, in a big way. Ensuring that I get enough electrolytes also (still trying to figure out what "enough" means, but...). Plenty of others.
Making sure that I only use "ancient" salt sources? Nope, sorry, not on my radar.