I think something is wrong! Yesterday I did my lesson (as everyday) and now my streak is back to 0 when it should be in 192 Why? What happend?
That's not the way the streak works. You have to earn at least one point each day from midnight to midnight in the time zone you made your account in.
This means you can do one lessons at 12:05 am on Monday and then do your next lesson at 6:05pm Tuesday (42 hours later) and still keep your streak.