Just now I founded that a domain hosted by cloudflare disappeared from the domain name list.
I checked my inbox and there was no email of abnormal cloudflare login.
I am sure that I did not perform the deletion operation, and my inbox did not receive the notification email of domain deletion.
Then I checked the audit log and found that a request to delete the domain name was sent from my account on May 27th(Below Screenshot). The user IP displayed is 127.0.0.1.
The problem now is that I want to re-add this domain name, but I need to verify that the DNS server is cloudflare. I has been transfered the domain register to cloudflare, So I need active this domain in cloudflare to change the DNS server.
The DNS server used by cloudflare for the domain name two months ago is no longer available today(jerry.ns.cloudflare.com, meg.ns.cloudflare.com), so I cannot make this domain name pass the cloudflare certification.