Seems like the main (only?) Card payment processor in Spain has stopped working, country wide, for one hour or two. That's a huge security/infrastructure problem.
News notes:
https://elpais.com/tecnologia/2023-11-18/problemas-con-bizum-tarjetas-y-datafonos-la-caida-de-la-plataforma-redsys-tumba-los-sistemas-de-pago-bancarios.html
https://theobjective.com/economia/2023-11-18/los-sistemas-pago-comercios-madrid/
https://www.elcorreo.com/sociedad/pago-datafono-redsys-servicio-de-procesamiento-tarjeta-espana-20231118144047-nt.html