It's maybe obvious, but in case anyone is interested, here is the little CSS code I added to avoid the image being deformed in the little circle icon:
.Avatar img { object-fit: cover; }
And the one to deactivate the link of the icon (in order to avoid linking to the profile):
.DiscussionListItem-content a.DiscussionListItem-author { cursor: default; pointer-events: none; }
Nice extension! (specially useful in the first day when you made half the topics and that it's a little cringe to see your avatar appear everywhere!)
EDIT (2022/11/21) :
The .Avatar img { object-fit: cover; }
solution is problematic, has the image appears pixelated in Chrome.
Instead, rather use this, which gives the same result and doesn't get pixalited in Chrome:
.Avatar img {
width: auto;
}
.Avatar.DiscussionListItem-thumbnail {
width: var(--size);
overflow: hidden;
}