Why my img element, inside a label, have a persistent white border?

i have a persistent issue.

Inside of my label, i have two <img> elements. One are absolute position, and have a strange white border, that's is not removed with css commands.

Print of the HTML inspector, showing my elements configs.

Here my CSS codes, actually, for both elements:

.imgBack { position: absolute; top: 0px; left: 0px; width: 100%; height: 100%; object-fit: contain; border: none !important; outline: none !important; } label * { border: none !important; outline: none !important; }