Volume automatically goes down while using wired earphones on my iPhone

I want to use In Ear Monitor Devices (IEM) on my Apple 15 Plus but whenever I use it, after few tracks the volume automatically begins to down to zero in a way that it does not increases. I have used all the tricks and methods to stop this such as deactivating headphone notification, reduce loud sounds, stopped some other audio related settings in accessibility but none of them worked. Whenenver I use the IEM with other devices it work flawlessly but not with my iPhone. Could me please suggest me why is this happening and how may I get rid of it as I want to use IEM being an Audiophile?

[Re-Titled By Moderator]