Indeed, HTTPs prevents the accelerating effect of the proxy.
On February 8, 2018, Google announced the death of HTTP sites.
For several years, Google has been advising Webmasters and the general public to adopt HTTPS encryption.
Not too long ago, they also informed HTTP users that the security of these sites was not optimal, offering them the ability to see that a page is not secure when they come across HTTP sites.
As of March 21, 2022, there are currently over 1.93 billion websites online and for Google, its dashboard used to track its usage rate shows that more than 90 percent of web pages viewed by Chrome are loaded in HTTPS (https://transparencyreport.google.com/https/overview ).
97 of the 100 most visited sites in the world were using HTTPS by default, as of January 1, 2019.
Also, if your intention is to save bandwidth and accelerate Internet exchanges, this will only be for a maximum of 10% of your users' navigation. “If you want to take full advantage of your Artica proxy's cache efficiency, it will be necessary to allow the proxy to perform HTTP decryption"