I was running a few speedtests and noticed I was only getting 400 Mbps down on gigabit hardwired, however other Speedtest servers are faster showing 650-800 Mbps. I have been able to recreate this several times over the last few weeks
Speedtest on Richmond Hill, ON Rogers Server:
Speedtest on Greensboro, ON Rogers Server:
That looks like an issue directly with that particular speedtest server. Either the Richmond Hill server is congested/overused or you're closer to the Greensboro server than the Richmond Hilll one.
It's always recommended that you test to multiple servers when doing a speedtest for the most accuracy. You can't always be certain that the recommended server will give you the most accurate results.