iPhone 15 Pro Max restarts, Wi-Fi/Bluetooth failing

I have an Iphone 15 Pro max. After 26.3 update, it started restarting. Also, the wifi module will be greyed out. When this happens the bluetooth also doesnt work. The problem became worse and the phone just kept restarting in seconds. However sometime it will work for few hours and sometimes the wifi will work as well. I ran the onboard diagnostics- resource inspector and it does say Bluetooth and wifi are fine. The issue was so bad that i ended up buying a new phone. I was wondering if there could be sporadic hardware issues where wifi and bluetooth get detected and then later disconnects.

Should i maybe wait for next update and see. I took it to apple store and few other stores and they said only way to check further is opening the screen.