Increased server responce time after change of Cloudflare account

I am struggling with an issue regarding the average server responce time in Google Search Console after I changed Cloudflare accounts for a domain. It used to be added in one Cloudflare account (I don’t have access to it) then I moved it to another Cloudflare account (I have access to it). Since that change, I see a spike in the average server response time in Google Search Console. The change was made on 16th of August. See the image.

Since I know that Google crawlers are located in the USA, I’ve tested the website multiple times using this service:
speedvitals .com/ttfb-test

I see that the average TTFB from Europe is great, but the performance from the USA is poor. Sometimes I see results higher than 1sec. (sorry but I can’t post another image because I am a new member… wondering how to describe my problem then…)

On the other hand, when I test a competitors website using this service again and I know their website is also using Cloudflare, I see good performance from America (even though their server is in Europe):

And now my question. I know that it’s always a matter of how the webserver is configured and how it interacts with Cloudflare, but I think I am obviously missing to configure some important settings in Cloudflare. I mean, the correlation of the increased average server response time when changing the Cloudflare accounts for the domain is very distinguished and one can clearly spot how the higher timings match the date of the change. Can someone recommend me something in terms of Cloudflare’s settings that can resolve the issue that I am experiencing? What am I missing?

Did you recreate the settings in the new account as they were in the original account?