I get it. So they can upgrade any time, but will be downgraded only at the end of the current period they are subscribed for. Thank you!

I have the same issue. Plus, when I upgrade to the best, most expensive plan, it doesn't recognize it. Instead it just thinks I'm subscribed to the less good plan, no matter how many times I upgrade. I "paid" the money in sandbox to upgrade. I also have them all in the same subscription group and ordered correctly. No matter how many times I change up or down to a different plan, it still messes up. Every time I click the first plan I signed up for, it chokes and says that I'm already on that plan even though I changed to all the other plans, one at a time.

I think I figured it out! If plans have not been approved by the app store, they show up in the list of available plans in the Apple provided plan management UI. However, if you switch to one of those plans in your app using a custom UI, the system does does not communicate with Apple that you switched to the plan. I had a couple plans that were approved, and its able to upgrade/downgrade those just fine, and the changes made in my custom UI show up in the Apple provided UI. However, the plans that had not been approved did not show as being selected in the UI at Settings -> App Store -> Sandbox Account Email -> Manage. They were available there as options though and could be selected! Very strange. There is one other issue... I don't get a "change" dialog. I just get a new purchase dialog most of the time. Will test more to see if I can figure out why.

No it's not. If they restore they will make another transaction that has a different id for the same thing. try weborderlineitemid or the date they paid for it combined with the plan.

Weird, having this problem too. I was trying to use a flutter plugin, removed it, trying to do it myself now. I don't know if maybe there's some remnant of flutter left. For me though, this is the order Registering client process with bundle identifier for PushKit voip in environment XPC PushKit connection invalidated from client

Ok I think if you delete app and reinstall it can help