"According to an R&D director from the Suzhou-based venture, on a clear 30-degree (86 Fahrenheit) day, a treated tank’s surface temperature can drop by roughly 25 degrees"

All I see in their claim is ambient temperature 30C, while surface heated in sun easily to 55C (or even more) with this paint claiming 97% reflectance to keep it at ambient temperature or slightly above.

Obviously the paint can't make surface cooler than ambient.