Thank you, Shameem, for providing the explanations. I reached out to the hosting provider, and they confirmed that there was no issue with the mail server. Additionally, I can send and receive emails from the email address I used in WooCommerce without any problems.
Yesterday, a new update for the WooCommerce Payments Plugin was released, and I was hopeful that it would resolve my issue. However, after updating, I still encountered the same problem.
As I attempted other solutions, I decided to reinstall the WooCommerce Payments plugin. Consequently, I deactivated and uninstalled it. Afterward, I initiated a test order and received email notifications on both the admin and customer sides. I placed 5 more test orders and got emails every time and all the orders were also logged in the SMTP plugin.
It seems the WooCommerce Payments plugin is causing the issue.
