The HSTS Preload site allows you to submit your domains to Chromium’s HSTS Preload list, so browsers will refuse to load your site over HTTP.
When Cloudflare Bot Fight Mode is turned on for a domain, the HSTS preload site can’t verify that the domain can be preloaded, claiming that there’s “No redirect from HTTP” (e.g. from http://example.com to https://example.com). What’s actually happening though is that Bot Fight Mode is intercepting the request and swapping the redirect for a JS challenge.
For a quick fix, you can turn off Bot Fight Mode, then add your domain to the preload list, then re-enable it, but I’m not sure if that puts the domain at risk of being removed from the preload list later. It seems like entries to the list are periodically checked to ensure they’re still valid.
Could the HSTS Preload checker be marked as a “good bot” and allowed through Bot Fight Mode? If it is the case that items on the preload list are periodically verified, there might be more bots to approve than just the one behind the public-facing website.