Does using Cloudflare Cache Reserve, improve SEO generally?

Hi
We have seen issues with Expires Headers, so we decided to try Cloudflare Cache Reserve, with the Auto Tiered Levels.

After using these, the GT Metrix Performance score dropped a little bit.

Does having the site thru Cloudflare Cache Reserve load the whole site from CF, or just a few files (like a CDN might work?). And does utilizing that (which can be seen in Waterfall), automaticaly give you a better SEO score, simply “by using it”?

We get around 90-98% Performance. Thru CF it was around 85%.

And no change in Pingdom scores at all!!