Cannot deactivate payment gateway programmatically

My custom theme has a filter to deactivate all payment gateways except Bank Transfer (BACS) on a specific condition, it works perfectly with all available methods (we have Stripe, PayPal and several others) but not with Satispay. Consider the following code:

add_filter('woocommerce_available_payment_gateways','umm_filter_gateways',1);
function umm_filter_gateways($gateways){
    if ( ! is_admin() ) {//front-end only
        $session = WC()->session;
        if ($session){//null check
            if ( $session->get( 'my_custom_condition_trigger' ) ){
                foreach ($gateways as $key => $value) {
                    if ($key != "bacs"){//if not BACS
                        unset($gateways[$key]);//remove gateway from array
                    }
                }
            }
        }
    }
    return $gateways;
}

Unfortunately all other methods are successfully removed under that condition, while Satispay remains available. I’ve also tried saving a custom debug option in the DB with

update_option('MY_DEBUG_LOG', json_encode($gateways));

before returning the $gateways array at the end of the function, and the array only contains the ‘bacs’ gateway, so my function works as expected. Why does the plugin show Satispay as an available payment gateway when it shouldn’t?