I don’t know how it works, but I know it doesn’t work fine. why?
1.1. when you search any keyword, the result in RELEVANCE, BEST SELLING and NEWEST ARRIVALS are the same. So these filters are bugged or the algorithm is really amateur.
1.2. To make these filters (RELEVANCE, BEST SELLING and NEWEST ARRIVALS) works properly, the user must refresh the page.
In categories ranking, many top sellers (top 3 sellers) were drag down 50-100 positions in a single night, even performing better than anyone. In my case, I had to achieve the top positions again in these last 3 weeks. In other words, I lost the performance I did over 4 years in a single day, because this algorithm.
In categories ranking yet, I can see many amateur sellers, with low ratings and almost no reviews in the top of many categories being consider Best Selling. Maybe fiver should change the filter “best selling” to “random selling”. Example: there is a gig with 27 reviews over 7 months in front of a gig which got this number of reviews in 4 days.
PS: all these tests were made with different connections, computers, devices, browsers, and clean cookies and caches. Everything was already reported to fiverr CS, but nothing was made (not even item 1.1 and 1.2).
In my opinion, fiverr is more worried to give a chance to mediocre gigs, instead focus on those good sellers who are the real source of income and reputation of Fiverr company.