Composite Blacklist which is a part of Spamhaus (also an IP blacklisting service), is a DNSBL blacklist. CBL lists the IP addresses that show activities such as being a spambot, being an open proxy SMTP server, or being a spam server.
We can assume that it should be similar to other popular DNSBL services since like some other blacklisting services. CBL listing criteria is undisclosed by CBL.
If you are still facing the issues with the IP removal after following the above steps, you can check these steps.
I hope you can now able to delist your site from the CBL blacklist. In case you have any queries related to your domain blacklisting, then please feel free to comment below or reach out to the Pepipost Deliverability Expert Team at dx(at)pepipost(dot)com.