I have tested on iOS15.4 beta4. I’m not 100% sure but the issue seems to be gone.

To Sam_V and Svantulden, Are your app using CoreLocation in background? In my case, the issue seems to be gone when I stop using background location even if cpu usage rate exceed 15%. But our app definitely need background location...

this is mistake. please ignore this answer.

We are facing similar issue on our application. Our application get killed on background on iOS15.2.1 and iOS15.3. It seems to be no problem on iOS15, 15.1. I guess high cpu usage rate threshold has been lowered from iOS15.2.x. (maybe from 80% in 60sec to 15% in 60sec!!). I hope this change will be reverted on future iOS release or I would like to know workaround this problem.