For the mentioned domain, the incorrect DNSSEC configuration is the actual issue.
The three out of four errors (the ones titled DNSLookupFailed) from your Let’s Debug link are all referencing the failure to validate DNSSEC.
For a list of potential options, I would refer to this post:
My personal advice would however be the first set from that post, to enable DNSSEC within Cloudflare, and then correcting the DS record through your domain registrar.