Subscription stats

Hello, in EventStore UI we see some “strange” statistics for certain subscriptions:


Here is ‘-72’ shown. We trying to find out what causes this inconsistence. Statistics retrieve via EventStore API returns such statistics for subscription group:
“lastKnownEventPosition” = null
“lastProcessedEventNumber”: 37,

I would appreciate for any hints or advice understanding such data inconsistence.

Additional info: we use Event Store 21.10.7.0 .