I think I might be tripping out here. I threw these in my bag as backups forever ago, and today I forgot my main pair. These don’t sound half bad through my FIIO BTR5. I think these came from Target like a decade ago, but I honestly don’t remember at this point. The tips are generic replacements from a 100 pack off Amazon.
There’s a long term theory in audiophile circles that as you progress through the chain of components that produces the audio every next part has less influence on the sound quality. So the source is most important, amplifier a bit less and speakers/headphones least of all. While I’m not sure I would always agree with that it still provides a pretty convincing reason for what you are experiencing.
You should really do a side by side comparison with a more expensive headphone to see whether you still experience this.
Still, I listen a lot to a set of TWS earbuds that cost me E15 or so. But I did add chi-fi comply eartips, drilled a little bass vent and put some foam inside to tune them. I think tuning in general is a little bit overlooked. The same driver can sound dramatically different.