Using Cloudflare Onion Service in Tor Browser

Cloudflare has Onion Services available, and is announced via alt-svc, but it seems that there is no way to configure Tor Browser to connect to Cloudflare's .onion addresses.

For example, when you go to cloudflare.com, browser console will show lines like: Alternate Service Mapping found: https://www.cloudflare.com:-1 to https://cflareki4v3lh674hq55k3n7xd4ibkwx3pnw67rr3gkpsonjmxbktxyd.onion:443

Even though I have "Prioritize .onion sites when known" enabled in Tor Browser, Tor Browser will still connect to www.cloudflare.com for webpage resources instead of cflareki4v3lh674hq55k3n7xd4ibkwx3pnw67rr3gkpsonjmxbktxyd.onion.

Cloudflare recommended Tor Browser 8.0 in their post (which was written a long time ago), but I am using Tor Browser 10.5a8.