Greasy Fork is available in English.
recreate subscribe button at end of works
< ao3 clone subscribe buttonについてのフィードバック
I think I've found the problem. after leaving a comment, the URL is just archiveofourown.org/chapters/ instead of /works/###/chapters. adding a user include of *://archiveofourown.org/*chapters/* fixes it.
works most of the time. button disappears after I leave a comment, though.