My question seems the same as this, which was not resolved.
I just added a domain with 4 DNS records, but Cloudflare somewhat added 200 random records. I don’t have any wildcard records as the server does not support it. This looks like there’s been an ongoing bug with Cloudflare DNS setup procedures.
The scanning tool is the best effort attempt at identifying existing DNS records, and whether it works is entirely dependent on your current Authoritative DNS provider’s response to DNS queries.
Even if you did not create the records, the existing or former Nameserver provider responded to those queries with an IP address or CNAME value.
Let’s say that you never created the FTP subdomain, ftp.example.com, but when we query for this record, the DNS provider responds with an IP of a parked/block/error page. The record would still be added to your DNS settings, this is expected.
Our documentation is getting moved a bit lately, and I’m not finding the article we had in place about DNS Scans, these are some of the references I found: