I don’t know anything more than what has been posted in the forum about it. The impression I get is the developer is choosing to focus on other things. Removing it from the default installation may be a way of gracefully phasing it out.
Last year there was a poll to gauge community interest in continuing to support the app.
The results from the poll were mostly in favor of continuing to maintain it, although there was an ensuing discussion regarding how it may not be that useful to get a notification when an update is available on a rolling release distro like EndeavourOS, since updates are constantly available at all times.
Later the developer mentioned a few times that the update notifier is not really needed due to this same reason, for example in these threads:
- Eos Update Notifier doesn't appear to be working? - #4 by manuel
- "EndeavourOS Update Notifier" notification doesn't work - #2 by manuel
More recently they explained the application will continue to get bug fixes, but isn’t being actively developed beyond that.
Like I said I don’t really know more about it than what is posted in the forum, but it seems like future development effort may focus on other apps instead of this one. That said, there is nothing wrong with the app (it’s not broken or anything), and can still be installed from the repo for those who want to keep using it.