After I entered my email/password, I was taken to https://kagi.com/html/signup -- a blank page. Zero content, even in the source code. Doesn't seem to be anything blocked by an adblocker or anything. Could be a transient glitch, or something that went wrong on the prior page, but wanted to mention it.
(For reference, I have uBlock Origin, NoScript, and Privacy Badger installed, and Firefox's "Enhanced Tracking Protection" was enabled, but none of them appear to be filtering or blocking anything on the signup page.)