alt Hacker NewsPorkbun uses cloudflare as their DNS backend, and has accidentally issued certs for domains hosted on them (https://news.ycombinator.com/item?id=40455508 was one instance).
Since cloudflare is basically the only registrar that will not allow you to host nameservers anywhere else I'd be weary to use them (even indirectly).
Realistically you should never use the registrars dns to begin with. But you can set your own dns with porkbun, I have customs dns on all of my domains. I especially have been doing that since the Namecheap hsts issue. Can't trust any of them.