TTFB is high with cloudflare proxy

I am using cloudflare for more than a year but recently i saw my websites’s TTFB is very very very high. Upon exmining i found when i am using cloudflare proxy the TTFB is between 5s to 6s while without cloudflare proxy it is giving me TTFB of 500ms to 1s. Couldn’t understand why suddenly this happening. Am i missing something on cloudflare panel?
The test website i am using is
test website

The below screenshots shows a TTFB = 2097 ms. Your site is developed using WordPress which is known for common/possible slow TTFB caused by third-party plugins. Try to disable your plugins one by one to check what might be behind a slow TTFB.

On another note, some images are very big in size. Try to optimize these images too and lazy load the other images on the homescreen.

For example, this image is around 1Mb in size which is too heavy for the web. It took 4549 ms for this image to load.