question

You are reading the input statistic of the queue which only ever increases (apart from being reset when a warmup time is set). You need a local counter, for example a label that you can reset back to 0 whenever the output gets closed.

I would also advice against using "await". It won't make a difference in this small example model. But it needs to store any variables from the code in a node so it can later resume the execution and is thus much slower than using messages or delayednodefunction(). With the latter you can call the same code again but pass in an additional parameter that changes what the code does. For starters, I would just use messages though.