Ubuntu 23 Application Getting Closed Automatically

 Most systemd services can be managed via the systemctl utility. In this case, we want to disable the systemd-oomd service. This can be done with:

$ systemctl disable --now systemd-oomd

You should see something like (depending on your OS):

$ systemctl disable --now systemd-oomd
Removed /etc/systemd/system/multi-user.target.wants/systemd-oomd.service.
Removed /etc/systemd/system/dbus-org.freedesktop.oom1.service.

You can then verify that the service is disabled, with:

$ systemctl is-enabled systemd-oomd

And you should then see:

$ systemctl is-enabled systemd-oomd
disabled

It is possible, however, that other services might attempt to restart the systemd-oomd service. To prevent this, you can 'mask' the service. For example:

$ systemctl mask systemd-oomd
Created symlink /etc/systemd/system/systemd-oomd.service → /dev/null.

And then systemctl is-enabled should now report:

$ systemctl is-enabled systemd-oomd
masked

If you'd like to later unmask (or re-enable) a service, that can be done with, for example,

$ systemctl enable systemd-oomd
$ systemctl unmask systemd-oomd

See man systemctl for more details; in particular, note the caveats regarding masking of systemd services.