I moved all my domains from google domains -> CloudFlare a few years ago. I haven’t had any issues other than CloudFlare is missing support for some tlds, mainly “.dev”
I think it’s still the case that you have to use Cloudflare’s nameservers, is that right? I’m considering moving domains from Gandi but it would be a lot easier if I could just point at the nameservers I’m currently using on Route 53.