Two read only views on the new Audit Log tab, both there so you can tell what happened in your app without guessing.
Audit log
Every genuinely critical action in your app is recorded here, automatically, and can't be turned off: a record being created, changed, or deleted in an admin only collection, a user being promoted to admin, demoted, or removed, a feature flag being created, changed, or deleted, maintenance mode being turned on or off, and an organization being deleted. Each entry shows who did it (either you, the project owner, or the signed in user who did it), when, and any relevant details, for example which flag or which collection. Filter by action type or by date, and page through as far back as you need. Viewing someone as another user already has its own separate, dedicated log on the Users tab, since that's a uniquely sensitive action on its own.
Error tracking
When a visitor's browser hits a real JavaScript error while using your published app, a small, anonymous report (the error message, where it happened, and a stack trace when one is available) is sent automatically to your own project, self hosted, never through a third party service. The Errors tab, right next to the audit log, shows the most recent ones so you can catch a bug you might otherwise never hear about. Only the most recent 200 reports per app are kept, and reporting itself is rate limited, so it can never be used to flood your project.
Tip: Neither of these views ever shows you a visitor's own record data, just what action happened, who did it, and when, or what error occurred and where.