Zend certified PHP/Magento developer

How to troubleshoot an issue where customers fill in different Shipping and Billing addresses but it comes through as same address on the order?

Magento 2.4.2-p1
Smartwave Porto theme
13 Amasty extensions 

I have the Calendar extension from Amasty as well as other Amasty extensions including One-Step-Checkout (this one is currently disabled but still installed), Shipping Area, Shipping restrictions and Shipping rules.

I have a gift shop so all of my orders will come through with a different Shipping/Delivery address and a different Billing address. What has been happening for months now is – most orders come through correctly (different Shipping/Delivery address and Billing address) but couple every day come through with the exact same address. This causes a lot of problems for us. I turned to Amasty for help but they said since we cannot reproduce it (the issue is very intermittent), they are unable to help.

How could I troubleshoot this to figure out where the issue is and how to fix it?