Notify users that a client update is available to their client channel if configured (toggable)
Notify users when their client has been out of date for more than X days (14 would match the *arrs) (no toggle - forced; old client versions are generally unsupported due to breaking changes and development)
Client Channel if Configured
Error Channel if no client channel?
If multiple clients are out of date - possibly consolidate to a singular notification
Possibly add banner to website notifying them their client(s) are out of date)
If multiple clients are out of date - possibly consolidate to a singular notification