/etc/systemd/systemd-{confext,sysext}.conf are likely just leftovers
from an older in-development version of the feature.
systemd-sysext/systemd-confext:
* systemd-sysext and systemd-confext now support configuration files
- /etc/systemd/systemd-sysext.conf and /etc/systemd/systemd-confext.conf,
- which can be used to configure mutability or the image policy to
- apply to DDI images.
+ /etc/systemd/sysext.conf and /etc/systemd/confext.conf, which can be
+ used to configure mutability or the image policy to apply to DDI
+ images.
* systemd-sysext's and systemd-confext's --mutable= switch now accepts
a new value "help" for listing available mutability modes.