a helpful feature, thanks admins for adding it!
one difficulty i encountered: it didn't work when clicking the button on the MacOS version of Safari, but it did work on iOS Safari. after subscribing on iOS, it shows as "Subscribed" on the MacOS version, but the button doesnt work to unsubscribe on MacOS either.
maybe its user error, maybe the software version, maybe something else entirely, who knows! the joy of debugging, haha.
anyway, just letting you all know in case anyone else reports problems. thanks again!