I am using Claire plugin in Crome, but it seems to me, the develeopment is cancelled. Do you plan to add http/3 for example? And other new features?
I don’t think this extension is made by Cloudflare itself…some developer might create a supported one in the future. But if you really wanted to check if a site was on Cloudflare I’d suggest using a NS lookup tool or looking in cookies etc.
Looking through the plugin page, it does appear that a Cloudflare employee has been responding to posts there. Someone there already asked about http/3 (QUIC).
It is in the Cloudflare’s github repo: