Yeah. I'm kind of flabbergasted by 99.9% of the comments on this topic, which assume the US is just chasing these things blindly without taking countermeasures.
The F-22 and other "stealth" jets can carry radar reflectors to intentionally make themselves EXTREMELY visible on radar.
Why would they carry such a thing? For one, it helps reduce the risk of accidents during training and other situations where they are flying in friendly skies. Two, helps prevent nosy enemies from learning about the true radar cross section of these planes.
It's hard to find concrete information on the USAF's practices here, for the obvious reasons.
The following is speculation, but: one imagines that the F-22/F-35/etc carry these as standard practice when not flying combat missions/patrols. One also imagines that they can be jettisoned midflight (like drop fuel tanks) in case e.g. a patrol turns into a spicy situation. That's a guess, I don't know if that's true.
Tangential, but you may also want to fill the skies with noise when flying a stealth mission.
The rationale being that you may be able to hear a cat's claws on floorboards in the middle of the dead night, but you'd never hear it in the middle of a rave party. So pairing F-22s with eg F-15s becomes a valid strategy.
And then the Chinese, knowing the US would use it to undersell capabilities…