By default Wordpress doesn't allow SVG upload for security reason. But if someone wants to support SVG upload in community portal, first it needs to support to the WordPress and then use the fluent community hook

fluentCommunitySVGSupport.php

function allow_svg_uploads($mimes) {
    $mimes['svg'] = 'image/svg+xml';
    return $mimes;
}
add_filter('upload_mimes', 'allow_svg_uploads');

add_filter('fluent_community/support_attachment_types', function($types) {
    $types[] = 'image/svg+xml';
    return $types;
});