Stealth for jets isn't primarily designed for plan view. (Referring to radar cross section isn't just a generic use of the term for "detectable area of return".)

Even if it was stealthy from above, it would be easy to identify and defeat, especially on the ground: just look for the plane-shaped area without a ground return.

Or separately, a pair of co-orbital following satellites would entirely defeat all (publicly known) radar stealth (with the transmitter offset from the receiver). The US admittedly has similar pairs of these for "scientific purposes". I assume the military/IC have access or have their own.

And synthetic aperture radar can be disguised such that its nearly indistinguishable from background noise. It's one of the features that makes it superior to old school dish radar. That's not even a secret. It's currently deployed throughout the military: ground, sea, and air. Space based platforms probably had it first.