Suspicious drop in addon downloads

I was checking some stats and saw that there has been a big drop in downloads for add-ons starting the beginning of June.

Some examples:
https://addons.mozilla.org/en-US/firefox/addon/copy-link-url/statistics/?last=90
https://addons.mozilla.org/en-US/firefox/addon/quickmark/statistics/?last=90
https://addons.mozilla.org/en-US/firefox/addon/omnisidebar/statistics/?last=90

its being tracked in this issue