I also opened up chromium to try it out, and got the same thing.
- - -
brave://settings/shields
- "Upgrade connections to HTTPS"
- - -
brave://settings/security
Advanced - "Always use secure connections"
- - -
Some combination of those, and [IIRC] a cookies setting, result in the browser being careful about a webpage that has a combination of HTTPS and HTTP (meaning, secure and not-so-secure) content.
For example, the FR webpage appears to be secure, but may have a frame (some area) that is not secure.
Possibly, the catch is the "Upgrade connections to HTTPS" - the browser cannot, because that "some area" is HTTP, not HTTPS.
Something like that. I do NOT know the exact reason.