I mean theoretically... I guess, if they do it right? It depends a bit. Some Linux distributions are crazy fast with patching stuff. And some stable channels have a really good track record of open vulnerabilities. Nowadays that's not the only way of distributing software, vulnerability might depend on your docker container setup etc.
Are there actual numbers what Cloudflare adds on top? What 0-days they focus on? I mean do they have someone sitting there, reading Lemmy CVEs and then immediately getting to action to write a regex that filters out such requests?
And how much does it cost? They also list the same ModSecurity in their lower plans. I don't think 0day protection would help people like me if it's $200 a month.
https://www.namecheap.com/support/knowledgebase/article.aspx/10128/2237/how-to-create-an-alias-record/
https://kb.porkbun.com/article/85-how-to-connect-your-root-domain-when-your-web-host-wont-provide-an-ip-address
Took me a while to remember... I think other providers don't call it CNAME flattening, but ALIAS records. And namecheap lists them in their documentation. You maybe need to look it up if you're interested, but I think they do in fact offer it. (I mean I'm not advertising for or against anything here. If you're happy with your provider and your setup works, that's fine. It's definitely not available everywhere.)