Hi Netzen,
If you mean OLS + LSCache, then I've not had issues with cloudflare and using the domainkey, likewise you can get a domainkey and use the image optimisation even on OLS. (domainkey required for that service too) I've not bothered with QUIC as in the past that was generally handled by Litepeeds own CDN. but QUIC is actually a technology and possibly supported by Cloudflare now (I don't know that's just my 2cents)
I tend to use LSCache for page optimisations, image compression and db management, beyond just it being a full page cache.