I don’t understand the first question. You think they only take 5% cut and absorb all other payment fees like VAT?
The second…is on their website? As well as their wikipedia. They handle Aeria, Steam, EGS and many others. I mean, if you know about Xsolla, how did you not see that they cover EGS, Steam etc?
Third, you can google Xsolla fraud/issue and find google pages of people complaining about it (especially on Reddit) charging them multiple times and being reported back tot hem by their banks/crads as fraudulent. If banks are blocking it for fraudulent reasons and so many people are experiencing these issues, that should worry people.
Tons more. You just have to google it. Many U.S banks themselves have Xsolla on automatic flag list and you have to call ahead of time to warn them, because of how sketchy they are and how many issues have been reported.