It states something about "your organisation's security requirements", do they document what requirements cause this rejection page? Some kind if changed default perhaps?
No, this is easily the biggest flaw in CAA - there is no way to discover which policy broke your access. I have reported this to Google multiple times, even sent this directly to a Google SecEng (a well known one) to route internally. The issue persists and makes configuring CAA extremely painful and error prone.
I am convinced there's someone who thinks debuggable security policies are a security risk and deliberately designs security APIs to be as inscrutable as possible.