Airpods 4/Pro 2 connection iss

Hi, I have this problem on my iPhone 15 Pro Max with AirPod Pro-2 as well as AirPod-4.

The AirPods would connect when I have YouTube app open and disconnect immediately once I close YouTube App. Is this something by design to save battery or something? How can have them connected until I take them off my ears? I don't want them go in and out of bluetooth connection.

Funny thing is, AirPods take a moment to connect back when I open YouTube app, sometimes it doesn't connect for long enough, until then audio plays on my iPhone speakers which annoys people around me. Why !