I would like to emphasize that my equipment has NOT changed. The Speedtest via Ookla is the same one used by COX. The download speed Ookla displays caps at 500Mbps This is the same app that is used when I was receiving ~700-900 Mbps back from June 2019 to September 2020. From that point, my download speed has not been more than 500 Mbps. My upload speed has stayed at around 35 Mbps. On 11/ 20, my download speed was at 95 Mbps and went up that day to 400Mbps. Speed check locations are mostly under Cox Server. I can't seem to post or paste a capture.
This appears as if you may need someone to look into your account. We would definitely be able to assist you with this. Please reach us on Twitter at @CoxHelp, visit us on Facebook, or email us at email@example.com. Please not personally. Provide us the name on the account with the complete service address with a link to this thread so we can get started. This way you can get the personal support needed to investigate this concern.