One side of headphone jack distorts/clips/cuts out. Help?

Okay, this will probably be a very odd issue to tackle. I don't know if anyone else has ever had this issue before with modern smartphones & IC based equipment?

Short version/TL;DR: Headphone jack is screwed - left channel works perfectly fine, right channel comes out distorted, clipped or completely cuts out depending on the gain of the track playing, and how high I have the volume turned up. I've tried everything software & hardware-wise I could think of (that was easy enough) to solve this issue, but unfortunately it continues to persist to this day.

Long version:

I have a Samsung Galaxy S9 that I've owned since June 8th, 2019 (so, well OOW). And it's an excellent phone. I don't think I'll ever be able to part with it. It does everything I could ask from a smartphone...or did..

In late August of 2021, I was hooking up my secondary 2.1 stereo system driven with a Fosi BT20A amp. I can't remember if the amp was on or off; but it was plugged in, and the volume was turned all the way down. I do however recall plugging in the RCA inputs via Y-splitter on the back of the amp, but upon plugging clumsily I had the left (white) male RCA plug touch the negative side of the binding posts (which are plastic and already had insulated wire hooked up to them, so no way they could've made electrical contact with the RCA), then corrected myself and plugged that RCA into the left side input of the amp.

Then I plugged the 3.5mm end of the input into my S9's headphone jack, and proceeded to play a selection.

The right speaker didn't produce any noise, or it did but came out distorted and was very quiet. There is no balance control on the amp, and I never adjusted any settings I already had set in my phone. The last time I hooked up my phone via headphone jack, my temporary system was working fine. Heck, even the day before I had this strange, dark and mysterious issue, my wired earbuds were working perfectly fine.

Today, the issue continues to persist although I have been using Bluetooth earbuds, or with my stereo system, a bluetooth receiver to compensate...it hasn't been the same ever since.

The issue I've been having with the headphone output on my phone is quite frankly, rather odd. When you plug in earbuds (like I do), the left channel plays perfectly fine, but the right channel is reduced in output either by 1/5, or by 1/2 the volume of the left depending on how you plug the headphone jack. And if I turn up the volume between 11-13/15 notches, the right channel starts to distort or even clips depending on the gain of what track I have playing. Beyond 13/15 notches the right channel will then clip hard and completely cut out, while the left channel remains unfazed by this issue and continues to play without ANY distortion. Again, as a recap, this was NOT an issue in the past.

I've tried everything I could think of to resolve this issue...hard resetting my phone, adjusting EQ settings, switching between mono & stereo, using the balance control, trying out different earphones that worked fine, cleaning my headphone jack & male plug on my earphones. Heck, I even went so far as to replace the headphone jack on my S9 with an iFixit replacement jack after the issue had started...NOTHING helped to this point!

BTW the internal speakers & earpiece in my S9 work perfectly fine. In fact I barely ever used them since I got the phone.

I've discussed this issue with the folks over at r/Galaxy S9, as well as on the discord r/techsupport server. But they weren't really all that much help.

This particular S9 has a lot of sentimental value to me, especially since I convert tracks into mp3 files to play them that way, and I'm just about reaching the 500 tracks milestone under downloads. Some of the tracks I have are from sources that have since been deleted from YouTube, and others are particularly difficult to find or reach. I also really dislike the fact that phones have notches & pinhole cameras on the screen nowadays, and they lack a headphone jack. I also particularly dislike the idea of using a dongle, since I'm the kind of person to charge my phone while having earbuds plugged in at the same time...really though, such solutions are a big No for me.

One solution I'm thinking about is buying a parts/donor S9, and swapping the headphone amp IC (wherever that may be), but I'm hoping it could be something as simple as a corrodeydoodle trace on the pin connections? I have no idea...

So PLEASE iFixit, help me surcease this strange, dark and mysterious issue for once!