combining timer and "install-mode: disabled" for a daemon seems not respected

when combining timer and a disabled install-mode entry in a snap, i see systemd start messages for the respective timer service in the system journal at package install time. the snapcraft.yaml for a package exposing this behaviour is:

https://github.com/ogra1/fonto-de-kerno/blob/main/snap/snapcraft.yaml

log excerpt at package install:

Apr 28 14:07:33 anubis systemd[1]: Started Timer updater for snap application fonto-de-kerno.updater.
Apr 28 14:07:33 anubis systemd[1]: Started Service for snap application fonto-de-kerno.lighttpd.
Apr 28 14:07:33 anubis systemd[1]: Started Service for snap application fonto-de-kerno.init.

(the "updater" was expected to not be started until "init" has finished and enabled it with a snapctl command)