Thank you for kind words and thoughtful response. I did some googling and found others are experiencing the same issue.
From what I gathered, the problems seem to be on YouTube side. YouTube blocks a lot of the public IP from executing the API. That explains the reason why the API works in development environment but fails once it’s deployed.
I’ve found 2 potential fixes:
Option 1: use a proxy with an IP address that hasn’t been banned
Option 2: someone suggests using a different api called youtubei.js
Later today I will give Option 2 a try. I have already sync’d the code on github, now this is a perfect time for me to learn how to fork the code so I don’t affect the deployed code.