This Taiwanese youtuber bought a ticket on Iwofly after clicking through on Skyscanner. At SEA, he was able to check-in. However, at the gate, he was denied boarding due to credit card fraud, according to the AS employee.
I actually knew someone who had a similar situation with WN. What I am curious is why he was able to check in and check a bag. Why wouldn't the system have stopped him earlier?

A lot of the comments online say "if he was able to check in and got refused boarding at the gate, Alaska must have oversold the flight and made this up". I am sure this was not what happened.

So, he ended up buying a ticket on the next flight. Then the IT issue happened

Things like this go viral quickly in Taiwan. Subsequently Iwofly requested him to remove the video and offered compensation. The news reports seem to say that maybe Iwofly got some 3rd party to ticket and the 3rd party was the one who used the fraudulent credit card?