Duplicate of this topic : Change PHP version of WordPress app - #2 by Mamie
See this comment : Wordpress needs a higher php version since 7.3 is insecure - Wordpress a besoin d’une version php plus élevée puisque 7.3 n’est pas sécurisé - #2 by Lapineige
Wordpress app already use a more recent Yunohost version. You might upgrade yours.