waiting for server response time is too long to load a page

waiting for server response time is too long to load a page

What’s the possible or the main reason to cause this
i am using litespeed cache for caching but most of the times there is always at least 4 sec initial delay
the server response time for some pages ar even at 7 sec when i use private browser page sometimes it’s fast sometimes it’s not
nothing worked even though i have a good score on pagespeed and gtmetrix

https://i.sstatic.net/1KCCOwV3.png

also in QUIC.cloud i see this

https://ibb.co/WvMnGwY
can it be from this ?

The page I need help with: [log in to see the link]