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That means the signal is entirely in the tin layer, if one is present. Not a good thing, as tin is not a very good conductor. Tin has about seven times the resistance of copper). So anything at 1MHz or higher should not have a tin layer. It needs to be bare copper. That means video cable, digital audio cable, RF coax or Category data cables all need to be bare copper. No tinned copper.
The way to defeat 'tin pest' is to mix tin with other metals, and these days tin is mainly used to form alloys - for example bronze, pewter and solders. Since tin is the most tonally resonant of all metals it is used in bell metals and to make organ pipes, which are generally a mix of 50:50 tin and lead.