Sharing my experience, so that it may help someone looking for this information.
I had booked TG tickets on TG website using a friends credit-card. He had to put OTP when paying. There was no indication in the booking process about CC check-in rule, when payment was being made.
I was confused initially whether the CC would be needed for check-in or not. The reason for confusion was following line in the eticket they sent later
THE PICTURE IDENTIFICATION, INCLUDING CREDIT CARD USED FOR ANY PURCHASE BY
PHONE OR INTERNET, SHALL BE PRESENTED AT CHECK-IN.
When I emailed TG customer service
[email protected] and
[email protected]
They replied the following.
Dear passenger,
Thank you for your email.
Please be informed that we have changed the policy recently and passengers no longer need to show the credit card used to purchase the ticket. Therefore, authorization letter is not needed.