Stealth No More: Here's How Russia or China Could Shoot Down an F-35 or F-22

This isn't exactly news breaking news.

Swedish SAAB, whose fighter jet (Gripen) doesn't claim to be stealth, started selling radar systems back in 2015 based on custom-manufactured Gallium Nitride (GaN) sensors that can detect "some" "stealth" fighters.

https://saabgroup.com/media/stories/stories-listing/2015-3/l...

https://www.janes.com/article/83778/us-to-evaluate-saab-gan-... (Oct 2018)

There's no reason, apart from extra weight to carry, that missiles/aircraft can't use more than one microwave band to track their targets.

High precision tracking is only required in the last mile or two. Low precision radar is plenty good enough to get the missile close enough for final high-precision tracking.