It's not accurate but it's not completely made up either.
There is a calculable power cost to each transaction. The work isn't just happening on one computer and God knows how many ledgers are out there right? To be able to pay somebody some fractional amount of Bitcoin to buy a pizza, The cost to have generated the Bitcoin the cost to check the transaction the cost to update the transaction and all the different places. We don't see the usage as a problem because it's tons and tons and tons of people paying for it.
But their calculating the water usage as evaporation for the power plants and evaporation from hydroelectric. Like the freshwater isn't returning to the system in large.
I wonder how much water was lost to make the pizza?