iPhone 15 pro max earpiece crackling speaker issue

Hi, has anyone encountered cracking sounds from the earpiece speaker of the iPhone 15 Pro Max when playing audio at a loud volume?

My unit, which I received on 29 September, exhibit this cracking/distorted sound when playing any sound with the volume above 60-70%, depending on the content. I am no expert but it seems to affect the mid-high range of frequency. Some songs on Apple Music, and voices on some YouTube videos are affected. Strangely enough it doesn’t seem to happen with iOS sounds like ringtones and alerts. The issue persists even without screen protector or any case on the device, albeit screen protectors and cases seem to further amplify the distortion.

I don’t know if this issue is software-related, perhaps due to the way the phone render out the sound, or if it is caused by internal vibration of other components, obstruction of the air (this model has really narrow speaker opening), or if it’s actually caused by a defective speaker unit.

I live in Thailand and I have already visited the Apple Store. They recommend that I refund the current device and buy a new one for replacement, as they don’t offer any replacement unit, unlike in other countries. The problem is that there is no product available for me to purchase at the moment, and I could be waiting for a month for them the become available. I don’t want to return my current device and wait without a phone to use until I can get a new one.

So, I’d like to figure out if this issue is indeed a defect or a normal behavior of this model. If it is the latter, I’d not bother with the return and buy a new one process.

Thank you

(i have mistakenly tagged a wrong phone model below)