Seems like they scrape social media, they say "We use our behavior-based Customer Satisfaction Algorithm™ to gather customer reviews, comments and opinions across a wide range of social media sites to help you make an informed buying decision."

if you click the question mark next to the number here: https://reviews.financesonline.com/p/libreoffice/

I would not bet on that number being at all reliable based on their vague description.