App Version: 64.0.3282.7 beta
iOS Version: 11.2, 10.3.3
Device: iPhoneX, iPhone7 plus
URL: any youtube.com video page

Precondition:
Make sure to sign in to youtube.com with any testaccount that didn't have used youtube previously. 
Copy a full youtube video URL into clipboard

Steps to reproduce:
  1. Launch Google Chrome
  2. Paste the youtube video URL in a new tab
  3. Scroll down the page and tap to expand the Comments section
  4. Tap in the text field "Add a public comment"
  5. Observe that "Create a channel" page is displayed
  6. Tap Cancel

Observed results:
Observe after Step#4: URL in omnibox is updated to m.youtube.com/create_channel/ …
Also on long tap on Back arrow at this stage doesn't show the youtube.com video page. Instead only NewTab page is seen.
After Step#6: NewTabPage is displayed.

Note: This bug can also be reproduced on Chrome Desktop with UA set to iPhone Chrome UA.

Expected results: After Step#6 Youtube video page should be displayed instead of NewTabPage

Number of times you were able to reproduce: 5/5
Bug reproducible after clean install: Yes
Bug reproducible after clearing cache and cookies: Yes
Bug reproducible on Chrome Mobile on Android: NA
Bug reproducible on Safari/Firefox: Firefox: YES, Safari: YES
Bug reproducible on current stable build (App Version, iOS Version): M62 YES
Bug reproducible on the current beta channel build (App Version, iOS Version): M63 YES

Link to video/image: https://drive.google.com/file/d/1k5ms8TTANbOBlV6h9tgXrSM5_22tPfZZ/view 

Please let me know if this issue needs tobe raised with youtube team.