Yes, since OpenSubtitles has changed API, and the one you refer to was with the old agents
Ref: Plex Media Server - #609 by drzoidberg33
If you still haven’t migrated towards the new native agents, your options would be 3rd.Party tools like SubZero ( GitHub - pannal/Sub-Zero.bundle: Subtitles for Plex, as good you would expect them to be. )