updatedMinTooLongAgo — The requested minimum modification time lies too far in the past.

Your incremental sync parameters are out of date — the Calendar can't return such old changes. To fix this, perform a full resynchronization for the calendar data. For instance, drop any stored sync tokens or time offsets and fetch all events anew using Riposte's calendar fetch endpoints. After a full sync, store the new token (if provided) to resume incremental syncing.