Redirect customer to cart page when 'Mixed Checkout' is enabled and product is added to cart

wcs_redirect_to_cart.php

<?php

function wcs_redirect_to_cart( $url ) {
	// If product is of the subscription type
	if ( is_numeric( $_REQUEST['add-to-cart'] ) && WC_Subscriptions_Product::is_subscription( (int) $_REQUEST['add-to-cart'] ) ) {
		// Redirect to cart instead
		$url = WC()->cart->get_cart_url();
	}
	return $url;
}
add_filter( 'woocommerce_add_to_cart_redirect', 'wcs_redirect_to_cart', 20 );