Speedtest hasn't been trustworthy for a while. Okla bought them and immediately started selling to ISPs nodes that they could install (probably just a container or something) that would sit as a "local" speedtest node, so you were testing your connection to the ISP, not testing your actual internet connection. (i.e. giving you the best possible results and what your ISP wanted you to believe).
Fast.com is slightly better in that Netflix spun it up to test your connection to their servers. So it's independent of ISPs - but then they built high speed optic lines to most ISPs so it's more like the second-best possible speed.
Accenture will be the same or worse. I don't trust it for speedtests anymore.