Returns the change in a player's stats since a starting point that you specify: the latest snapshot diffed against the most recent snapshot at or before that point. Provide exactly one of duration (for example 48h, 10d, or 2w), from (a Unix millisecond timestamp or RFC 3339 string), or marker (the name of a saved marker). The from and marker forms require account ownership or the All Sessions permission, as do duration values outside 1-24 hours, 1-30 days, or 1 week and up. The delta is a recursive diff: unchanged fields are omitted, a changed numeric stat is the bare difference (new minus old, e.g. 50 or -3), and a field that appeared, disappeared, or changed non-numerically is { "old": <previous or null>, "new": <current or null> }, with old null for a stat absent from the baseline snapshot.