What is wrong with my site

I have optimized my site in every possible way to load fast.
Improved GTmetrix
Improved GooglePageSpeedInsight

Still load time is shown to be 5.1 sec of first byte. I am using cloudflare CDN

https://groupbuyanytool.com/

Why are videos not autoplaying on iOS devices? They were a few months ago. They still play on my iOS device. What is happening at webpagetest in this regard? Thanks in advance.