Stats total count decreases on increasing the date range for prom counter

I have a simple prom counter linked to stats visualization, with total as a reducer function. The total count however decreases when I increase the date range.

I must be missing something.

I changed the query to

increase(http_server_requests_seconds_count{uri="/api/otp.send", status="200", outcome="SUCCESS"}[$__interval])

The total count came out correctly.