14" MacBook Pro 2021 sudden loud sound

When I start listening to Apple Music, the music will be played at full blast, then gradually lowered to my system volume setting in about a second.

When I wake up my MacBook from sleep, if there is any notifications, the notifications sound will be played at a very large volume (it can be heard in the entire house). If the speakers break due to this, will it be covered under MacBook's 1 year limited warranty?

I've updated my macOS to the latest version, restarted the computer many times, tried this on both headphones, laptop speakers and Bluetooth speakers, on battery and on power adapter, on Wi-Fi and offline environment, on laptop screen and external screen. The issue is intermittent.

The problem can be reproduced on my friend's MacBook Pro 14" and 16" as well. I bought mine online and he bought it in a local authorised reseller.

The problem started on day 1, and many other Redditors and community members have encountered the same issue, so I believe it's a software issue.

May I know how to fix this?