Review sample in "Processing Mode" sounds way better than the RAW recorded audio

It is super weird,

here the full explanation:

I recorded my piano sound . Listen to it while playing sounds nice. But when Iam done recording and I listen to that audio again it loses the warm sound and kinda feels tinny.
I recorded something again later and because I accidently plugged the left and right channel into my interface incorrectly , I wanted to swap those channels to correct them under " Audio - Processing - Stereo Flip "
Than there is a play button you can press to review what you just did. And not only that yeah , the process worked… the sound is correct again with all its warm sound back and its no longer tinny.
But guess what, if I go back to the actual audio it is not fixed.

I have no clue what it could be. Any suggestions ?

Kind Regards.