To add the vendor logo beside sold by vendor name and on vendor tab –

add_filter( 'mvx_sold_by_text', 'vendor_logo_before_sold_by', 10, 2 );
function vendor_logo_before_sold_by($sold_by, $id) {
    $vendor = get_mvx_product_vendors($id);
    if($vendor)
        $image = '<a href="' . $vendor->permalink . '"><img src="' . $vendor->get_image() . '" style="width:30%!important;max-height:30px!important;object-fit:contain!important;"/></a>'.$sold_by;
    return $image;
}
add_filter( 'mvx_before_seller_info_tab', 'vendor_logo_before_product_vendor' );
function vendor_logo_before_product_vendor($logo) {
    global $product;
    $vendor = get_mvx_product_vendors($product->get_id());
    if($vendor)
        $logo = '<a href="' . $vendor->permalink . '"><img src="' . $vendor->get_image() . '" style="width:30%!important;max-height:30px!important;object-fit:contain!important;"/></a>';
    return $logo;
}