In the new PR experience, the "Ignore whitespace" option is moved under global settings.
In the Old PR experience, this option is available for each diff under ... option
This impacts some customers who generally keep the "Ignore whitespace" option 'off' as per their workflow. However, they need to enable the option while reviewing a file with lot of whitespaces.
When the user is in the middle of reviewing a PR, if he sees a huge file with tons of whitespace changes, he has to scroll all the way to the top of the PR to enable the option and then go back to file which he was reviewing. This is annoying to the user.