Limited download tests...upload always higher

I have AT&T gigapower internet, and I regularly get 400Mbps when I iperf to my local machine over my wifi on my iphone 7 plus, but this app always says my download is around 110Mbps even though it properly tests the upload at 300-400Mbps like the iperf results.

I had the same issue with iPhone 6, upload was always 200+Mbps, but download was always 110Mbps.

Is there some sort of internal limit to the apps download logic?

markley268 about Speedtest by Ookla, v3.7.7