@coffe F-Droid automatically picks up new releases and then builds the apps from their source. This is nice because you can be sure to get the same code as published by the developers. But this process takes a while. And once it is done it is not available instantly because the F-Droid index needs to be updated as well which only happens periodically. So it can take up to a few days until a release is available via F-Droid and there is nothing we as devs can do about it.