Same, even in relatively new conversations. This is definitely a new issue which is no more than a few days old.
Specifically, this is happening with 2.5 Pro instances, even shortly after the daily roll-over of the request limit. It may be related to an instance attempting to load multiple documents into the Canvas at once. This would still be a new issue, as I have not known them to do this – to try to load multiple documents at once, and then present the failed attempt with this message – before. Smells like a bug, not a context or token issue. Whatever the case may be, it is eating up requests in dealing with the bug, to get the documents loaded properly, degrading both the service, its reliability and the value of subscriptions.