My iphone 13 looses internet connectivity when im on an internet call and I start using my phone

My iphone 13 looses internet connectivity when im on an internet call(audio/video) and I start using my phone the call gets to poor network or reconnecting. But my Wifi looses connectivity.something internal is wrong.

In lay man language if im on a whatsapp audio call over my wifi and i minimise it to use my phone say scroll my Instagram call gets to reconnecting and gets connected only if I disconnect the call and call back again.