For centering all images, in all notes across the vault, remove the cssclass from both sections so
.markdown-source-view.mod-cm6 .cm-content > * {
margin: 0 auto !important;
}
.markdown-preview-view img {
display: block;
margin-inline: auto;
}
I haven’t tested all scenarios and on the phone now, but that seems working.
This is also an option to center all images, in all notes:
img,
.markdown-source-view .cm-content .image-embed {
display: block;
margin-inline: auto !important;
}