I'm 4 months in my electrical apprenticeship. We've used dielectric grease already and oddly it was indoors in a dry area. I didn't know this, but when dissimilar metals come in electrical contact, over time one of the metals corrodes the other. It's called galvanic corrosion.
We used dielectric grease in aluminum lug connectors, actually they came with it already in specifically to prevent galvanic corrosion.
And dielectric grease doesn't affect conductivity either. We used it directly on the mating surface contacts for high voltage cable in a nursing home to power the ventilation system. So if its used in that situation, it must be safe to use lol!