IIRC, it was in a Reddit comment from their representative replying to a user who claimed they got banned recently. I think the user stated that they did use a lot of data in a month, but never explicitly stated the number of it, then the Windscribe representative claimed it was 60 PB/month. Other reports claimed the users only use 10 TB or less,s so I'm not sure the exact limit for their "unlimited" plan. I guess I'll look for other services if they keep being hush hush about it.