DursunCan One of the most common reasons here is that Cloudflare can in fact increase the TTFB (Time To First Byte) of any website it serves.
However, I do not see any evidence of that here
And the TTFB is a little high in my view, but not overly
However, you really should pay attention to this
Note, that some testing sites, even if you have GZIP enabled, will still complain it's not there because the content is served slightly differently by Cloudflare. In this case, Cloudflare uses Brotli by default (unless you disable it), but you do not have any expires headers set, meaning the content will never be cached fully.