So what seems to have happened is that N number of EVs - where N is unconfirmed in any of the articles I have seen but all have the same photo of a white Tesla Model X - which were submerged in salt water storm surge for many hours, experienced battery fires due to this corrosion / conductive water intrusion following a hurricane which had the worst level of storm surge in a populated part of Florida that I can remember in my lifetime.

I know that at least some gas car fires also happened in the aftermath of this storm, submerging even a standard 12v car battery in salt water is inadvisable.

I'm not sure what we can usefully draw from that, other than to avoid leaving EVs in areas expected to be submerged in salt water, but that's generally good advice anyway.

I do think the difference in how these fires are managed versus a gasoline fire should be considered. The most interesting thing I have seen to deal with this is a fire department that just had several car-sized metal dumpsters. Drop the car in the dumpster, fill it with water from a firetruck, and come back in a day or two.