I thought that as well. Totally anecdotal, but after switching off of CloudFlare and onto a dedicated IP, our rankings increased within 2 weeks. We track algorithm changes through SEMRush, who did not report an algo change around the time the rankings increased. In addition, we actually saw an increase in page load times because the assets were no longer being served via CDN.

https://serverguy.com/case-study/cloudflare-seo/ . It is well known in the SEO arena that your neighbors affect your SERPS. Cloudflare has an open policy on who they allow on their service where AWS, Akmai, Fastly, etc have acceptable use policies banning services like online gambling, online pharmancies, etc.

Google doesn't release any information about how they rank sites but it is reasonable to assume there is a network/IP reputation score similar to what email providers use to combat spam.

Interesting. I know CloudFlare's neural policy but never thought about its effects on ranking. It explains a lot.