Hey, could be the speedtest-cli program changes units when you get to high speed connections. I've only got 30mbit down so can't test it, could you install speedtest-cli by doing:
pip3 install speedtest-cli
then post the output of:
speedtest-cli --json
so I can see what's going on with the results. You may potentially want to specify a server ID when running that, as it will pick the closest one to you and may reveal your location.
It's the server ID from the XML file. So you could put: "7028,11445,17418" as the value in the settings card, and each time it runs it will pick one of those 3 randomly.