Reviewing experiences effects on applying process Can reviewing experiences for top notch journals in a specific field be considered as a distinguishing and effective factor for the applying process?

I've read somewhere that having a fertile record in sites such as Publons can have a positive effect for applying for, e.g. a PhD position.
It's a very weak positive signal.  

Being invited to review in a field's top journal is a sign that somebody thought of your name when seeking people with deep expertise in a specific domain of study.  This is clearly a good thing when applying to a PhD program (but would definitely not be expected from an applicant).  That said, inappropriate reviewer selection happens all the time, so as I said, it's a very weak signal.