Email notification not receiving for admin and customer

Hello,

The shop owner as well as the customer does not receive an email when a new (invoice) order is placed. it was working fine, but recently I’ve noticed this issue. But the shop owner receives the email regarding the Product out of stock information.
I’ve checked with the email log plugin. But it also logs only the out-of-stock mail.
There are no issues with the emails when we try to place an order by bank transfer, COD, and any payment methods.

Looking forward to your feedback. Thank you!