5 of the 8 teams in playoffs are from NA and EMEA and 2 of the only 4 matches that have happened with the crowd have been NA vs EMEA, pretty hard not to bring it up. If you didn't want an answer based on what we've seen so far, kind of the wrong time to ask.
They're not just biased, in Fnatic vs XSET they were completely silent any time an XSET player did something significant, and they'd pop off if an EMEA player got even one kill (not an exaggeration). It was only slightly better in Optic vs TL, presumably because Optic has been a top team for a while now and have had great performances this year. I get that Alfa is the only Turkish player in the event, obviously the Turkish crowd will favor him heavily, but having a reason for the bias doesn't really make the crowd experience any better.
It's pretty lame, doesn't really matter if the bias would occur in reverse at an NA venue, which is conjecture. I imagine teams like TL or FNC would definitely get cheers even in NA.
Only upside is XSET leaning into it and antagonizing the crowd, because the crowd would be against them anyway.