Customize order of Restrict Content Pro gateways.

functions.php

<?php

add_filter(
	'rcp_payment_gateways',
	function( $gateways ) {
		$order = [
			'pronamic_pay_credit_card'  => 0,
			'pronamic_pay_direct_debit' => 1,
		];

		foreach ( $gateways as $key => $data ) {
			$gateways[ $key ]['order'] = array_key_exists( $key, $order ) ? $order[ $key ] : PHP_INT_MAX;
		}

		uasort(
			$gateways,
			function( $a, $b ) {
				return $a['order'] <=> $b['order'];
			}
		);

		return $gateways;
	},
	100
);

style.css

#rcp_payment_gateways {
	display: flex;

	flex-direction: column;
}

#rcp_payment_gateways label[for="rcp_gateway_pronamic_pay_credit_card"] {
	order: 5;
}