The systemd (example) service file:

wildfly-26.1.2.Final/docs/contrib/scripts/systemd/wildfly.service

uses a legacy path in the PIDFile reference:

PIDFile=/var/run/wildfly/wildfly.pid

This results in the systemd warning

/etc/systemd/system/wildfly.service:11: PIDFile= references a path below legacy directory /var/run/, updating /var/run/wildfly/wildfly.pid → /run/wildfly/wildfly.pid

The fix is trivial by changing the line

PIDFile=/var/run/wildfly/wildfly.pid

to

PIDFile=/run/wildfly/wildfly.pid