This page covers a lot of Cloudflare issues:
https://git.kescher.at/dCF/deCloudflare/src/branch/master/subfiles/rapsheet.cloudflare.md
The 2nd link on that page goes to:
http://cryto.net/~joepie91/blog/2016/07/14/cloudflare-we-have-a-problem/
which details the traffic exposure to #Cloudflare as a consequence of Cloudflare holding the keys & terminating the tunnel (thus performing the decryption). Indeed the padlock is misleading as most users believe the tunnel goes all the way to the source website.
edit: BTW, I see that you are on #lemmyWorld. You might be interested in knowing that that’s also a Cloudflare site. Cloudflare sees your login credentials, your IP address, and everything you do with your lemmy account. As far as gatekeeping goes, Lemmy World has been manually configured to be less exclusive than default-configured sites like stackexchange. E.g. I am blocked from stackexchange but not from lemmy world.