Power BI runs query multiple times on backend?

I see the same behavior when the query uses the Web.Contents ("Web" datasource) function. I have a REST web service that returns a CSV formatted payload and my logs show 3 executions of the same data query without regard of the payload size.

When the payload size is really small (3 rows in the CSV content) the 3 query runs happen on every "Refresh". When the payload is larger (10,000 rows) I'm seeing 6 query runs where the first 5 seem to be cut/stopped by Power BI around row 5,000 on the first 5 runs (getting a "Connection Reset by Peer" TCP/IP error on my server) and only the run #6 completes 100% (all 10,000 rows).

For comparison, if I invoke the same REST function with a web browser my logs show only one query (as expected) with a 100% transmission of the content without any TCPI/IP errors.