Hey there, @Tr_n_Qu_c_Huy and welcome to the Community 
I am so sorry for the confusion!
The thing is that this is a field to add the URL to your LinkedIn profile, but not to the reviewer’s profile. This is why the same URL is added for all reviewers right away:
Unfortunately, it’s impossible to add individual links to the reviewers’ LinkedIn profiles, but I’ve added this idea to the Wishlist on your behalf - Individual link to the LinkedIn profiles of reviewers.
Please let me know if this explains things or if you have any further questions 