In-ear headphones emit sound on one side, and with increasing volume more and more interference?

Hi, I used in-ear headphones (Teufel Move), but after someone from my family took them and connected them to a laptop, I can hear normally on the right side and VERY softly on the left.

The left side is about 5x weaker than the right side. (Tested with balance controls)

In addition, as the volume increases, I have more and more interference.

What I have already done / can exclude:

Headphones worked perfectly before that
Are not contaminated
Balance regulator is normal at 50/50
Jack also works (same problem on laptop, PC and mobile phone)
Teufel Move have no internal memory (as far as I know) and can't be reset
Buttons (volume up, down, next track) work
No cable break
I would also rule out loose contact

My guess would be clipping, but I can be wrong.

Did you at least pay a lot of money for it?

My 19.90 parts run wonderfully.

Cost around 50 euro on the market.