Allow iframe for the user_description field. It's not recommend due to security

functions.php

function um_wp_kses_user_desc( $tags, $context ) {
	if ( 'user_description' === $context || 'pre_user_description' === $context ) {
		$allowed_html = UM()->get_allowed_html( 'templates' );
		if ( empty( $allowed_html['iframe'] ) ) {
			$allowed_html['iframe'] = array(
				'allow'           => true,
				'frameborder'     => true,
				'loading'         => true,
				'name'            => true,
				'referrerpolicy'  => true,
				'sandbox'         => true,
				'src'             => true,
				'srcdoc'          => true,
				'title'           => true,
				'width'           => true,
				'height'          => true,
				'allowfullscreen' => true,
			);
		}
		$tags = $allowed_html;
	}
	return $tags;
}
add_filter( 'wp_kses_allowed_html', 'um_wp_kses_user_desc', 10, 2 );