I saw many people had a problem with their API gateway services on their website which got blocked by cloud flare. However, I saw many people recommending whitelisting ips which has no effect and not help to solve this problem even those who are expert and answers most questions on the community.
Here is the solution:
If you got an error with your website or payment gateways, make sure you select TLS v1.2 instead of 1.3 which blocks most connections related to older versions if you select TLS v1.3.
That was all! Hope your problem got solved!