At the moment, F-Droid pushes the latest pre-releases of Joplin, which is certainly beneficial for those who want to have the cutting-edge experience, but at the same time somewhat discriminates against users who prefer stability over functionality, because right now they are forced to choose between using the latest Beta or complete disabling automatic updates for all F-Drod apps (or go to Play Store, which is inappropriate for some of the F-Droid users).
To make everyone happy, I propose just adopting the approach of Aurora Store's developer, who does not maintain a separate channel for pre-releases, but instead assigns a “Suggested” label to the versions considered stable. As a result, by default, F-Drod installs only the suggested stable release and does not update it until the “Suggested” label moves higher. At the same time, impatient users can simply toggle the slider on the app page to unblock unstable updates of Aurora Store and always have the latest Beta.
In the case of Joplin, it's worth it to just sync the “Suggested” label with the latest version from Play Store.
The technical side of this approach is documented here: