This article in an Austrian firefighting journal (unfortunately only in German), talks about a patent for the measure to "extinguish" a vehicle that is causing problems after a fire by cooling it in a closed water tank. A company that produces a special container called "redboxx" for cooling burning electric vehicles has patented not only the container but the whole principle of dipping a burning car into a container filled with water. Fire departments in Germany had to pay a "licensing fee" of 1000€. The patent was granted for all European Union territories.
Fire departments are advised to use other means of extinguishing to avoid the fees.
In my opinion this is a very problematic development. As far as I know this is the only reliable method to extinguish the burning batteries of an electric vehicle, but it could be shut down by the fees.