Volume is randomly blasting

So I have the iPhone 13 I have had it for one day and when I am at work I like to scroll the Instagram and things like that but not supposed to so I keep my phone mute or I raise it by one notch( I use the command center out of habit since my last phone the buttons did not work) but randomly it will go to full volume and blast what ever music was on the post and The Whole office can hear it. it’s not the case I took it off thinking it was that but it was not and I happened 4 times today. And Ian not alway in my phone just for 5 mins every hour. And the volume is not going up with the white bar like if you use the buttons it just goes loud. Please help or fix the bug