I wouldn't describe your list of subscriptions as "unrelated" to an attempt to subscribe to a group.
But if I click on the button when I am logged in, I end up on my own list of subscriptions, with no indication whether I've subscribed or not, or any mention of the group I'm trying to join.
If in fact you were already a member of the group in question then this is probably a reasonable choice of landing page. Possibly in fact it defaulted to your home page (which is likely to be your /groups page). Maybe your subscription page for that specific group would be a better choice.
Any insight into what might be going awry there?
If you were not already a member of that group then I'd agree that something went awry. I haven't tested this, but if you can confirm whether or not you were already a member of the group that would be useful information.
Shal
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