This is not a regression. Tested in //UE5/Release-5.0 CL20979098
Web Browsers widget components stop accepting input when toggling visibility with a delay if there is more than 5 browsers. This only occurs when there is a delay between the changing visibility.
All browsers can be interacted with.
All the browsers after the 5th browser can not be interacted with.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-171882 in the post.