When I open PDF file from Apple Mail I got black line over hyperlink

Hi guys,

I have an issue when I open a PDF file from Apple Mail, I got a black line over each a hyperlink. I tested to open the same PDF file from Outlook or other PDF applications, didn't see it.

Moreover, I tested on my iPad mini4, I got the same issue.

My colleagues tested to open the same file on their Android device, they didn't see the issue.

My iPhone and iPad is on iOS version 11.2.6.

Do you have any suggestion to solve this?

Thanks,

Tro Dechmontri