I am a user of F-Droid. Something happened a while ago and I had to reinstall or clear the storage to get it to work again. However, some of the apps that I installed from fdroid have added permissions, and I did not want them to update, also k-9 mail app has changed the UI so I was using the version just before the change happened. Well as soon as I launched f-droid it immediately downloaded and started installing all the apps I did not want updated. I have a fast wifi connection so it did this all very fast before I could get into settings and disable the auto install default behavior. If this bothers you as well, you can install Droid-ify, its basically a front end of f-droid. https://droidify.eu.org/ and its default is to check for updates but not install. :-)
I did mess with obtainium, which is really cool, but I would like to know what permissions are added before I install/update. It seems like every opensource app has permission creep. lol