Argh, good catch! It's actually a regression from the recent styling update.
- The plugin maintainer has permission to hide and show any approved version.
- Only the directory admins have right to hide and show the whole plugin.
But, the button to actually hide the version has CSS class called 'hide'
named after the action. With the recent switch to bootstrap based
theme, CSS class 'hide' got special behaviour. As you can guess,
bootstrap silently hides such element. So if you inspect the row
with the action links (Learn more / Edit details etc), the link "Hide" is
there. It's just hidden.
I have a patch ready at my notebook and will deploy it during the next regular
update of the moodle.org site (could take a week or two).