wanted to report the same issue before but thought the current behavior may be good
The recharging behavior is good, but a user should be able to stop it from trying to recharge. Currently, once the subscription has expired, Stripe will keep charging, but there's no way for the user to stop it.
after grace period xenforo downgraded the user
I don't think XenForo has a grace period. Stripe typically charges the user before their subscription actually expires in case there's an issue.
he was charged for the cancelled subscription as well resulting in a double charge.
Right, that's the sort of issue that arises. I believe XenForo will try to credit the user for both charges, but it's still unexpected, and both subscriptions will continue indefinitely.
But you‘re able to and should cancel it on their behalf from your Stripe dashboard.
Depending on the country, what sometimes happens is the charges fail because users don't have enough funds in whatever account they were using. In a panic, they contact us to try to get automatic charges to stop, but there's often no reasonable way we can respond before the next attempted charge. That's really not a great situation, especially if it's happening outside the work hours of both our company and the user's bank.
This isn't really a problem in the US since people typically subscribe with credit cards, so we can simply refund them. For someone in India, though, this scenario can cause pretty significant problems.