AMP auto redirect breaks website

[0mMdy8R6uS8xpP]

Description

Brave browsers AMP auto redirect feature broke a website

Steps to reproduce

1. Turn on brave AMP auto redirect
2. Go to https://m.nocutnews.co.kr/news/amp/6227673
3. The url becomes https://m.nocutnews.co.kr/news/<%= resulting in broken site

Actual result

I went to a google AMP page and brave browser broke the website, turning off AMP auto redirect feature fixes this

Expected result

Brave browser should redirect to https://m.nocutnews.co.kr/news/6227673 instead of https://m.nocutnews.co.kr/news/<%= when user tries to access https://m.nocutnews.co.kr/news/amp/6227673

Reproduces how often

Easily reproduced

Desktop Brave version (brave://version info)

v1.70.126 on Windows 11

Android device

• Brand/model: Galaxy A23
• Android version: 14

Channel information

• [x] release (stable)
• [x] beta
• [x] nightly

Reproducibility

• [x] with Brave Shields disabled
• [x] with Brave Rewards disabled
• [ ] in the latest version of Chrome

Miscellaneous information

No response

[ShivanKaul]

The AMP canonical link element is malformed for the website: <link rel="canonical" href="https://m.nocutnews.co.kr/news/<%= Index %>"> Given that the website does not follow the AMP spec, I'm inclined to call this a wontfix. Thoughts @boocmp?

[boocmp]

Yes it is. It references to <link rel="canonical" href="https://m.nocutnews.co.kr/news/&lt;%= Index %">.

[ShivanKaul]

I wonder if we could do something clever here: if the target URL after a de-amp results in an error status code (4xx or 5xx), then we fallback to the original URL. WDYT?

[ShivanKaul]

@boocmp pointed out that in this case we should just have a check that the regex matches the href, and that would've resulted in the existing fallback.

[ShivanKaul]

additionally we should also do https://github.com/brave/brave-browser/issues/41665#issuecomment-2418275201