I figured...I was just being cute....
Imagine, a radar coating that is diminished by rain!
This thing is a behemoth. Built to avoid radar and present a smaller RCS signature. Still can’t completely hide from L-band or lower frequency radars, though. It is an anachronism.
When the product development cycle is something like twenty years, it's very likely that -- by the time an aircraft enters service -- it's already technologically obsolete.