Iphone 15 pro max Bad sound quality

Hello Recently just got my iphone 15 pro max from ee as a contract.

I was really happy with it until I decided to listen songs from the speakers of the phone.

Sound is really bad quality I can hear a cracking sound or Not sure how to describe it but like vibrating plastic .

When I been asking about sound quality of iphone ee customer service told its one of the most nice sounding phone and loud. Honestly is not that loud, and sound quality well ... Notification are also really quiet even when turning Attention Aware Features I can barely hear sounds outside when someone calls me or sending text,