A few months ago, the APO team (including @yevgen) implemented a fix to enable caching of query strings, like fbclid and UTM. It was working great until recently.
Today, I discovered that all fbclid query strings with any parameters (?fbclid=xJDJDxXmxmbeEFDFw) are being cached individually and return cf-cache-status: MISS on a second pageview with different query string parameters. In reality, every request with ?fbclid, regardless of the parameters, should return the same cache entry.
https://www.example.com/?fbclid=xJDJDxXmxmbeEFDFw -> cf-cache-status: MISS https://www.example.com/?fbclid=bvgVERERWFVVSDDS -> should be cf-cache-status: HIT even if the parameter is different, but also returns cf-cache-status: MISS.
I know this has been fixed before as I was the one who had opened a ticket (APO and Query String Cache). I’m not sure why it isn’t working anymore, but it is very important to have it working properly, especially for sites that receive lots of Facebook traffic (like mine).