Creating releases involves creating a tag, then manually editing a draft release and manually hitting publish. We noticed with 3.0.4 (which had a longer changelog to edit) that when people opened the mod manager in the mean time, the update was still presented even though the release was not published yet.
The issue resolved itself once the release was published.
Ideally the update system could be improved to not detect these "incomplete updates".
Reports of this on the discord: