(Just to get this out of the way at the start: I tested my download speed from itch.io by downloading an actual game before I made either of my posts here. Both times it downloaded at max capacity for my connection. The reason I tested that is because I take this seriously and wouldn’t just dismiss the topic sight unseen.)
Well… I cannot speak for the itch.io staff but my personal guess would be that there’s no answer from itch, because the issue you and the others have/had is “my download is slow” (more on this later). I do not want to make it seem like your issue isn’t important, but as far as we know everyone else’s download is running fine. Meanwhile, there are hundreds of independent developers who have important questions concerning their taxes, some crazy people who want their money back, and other things that involve money.
Now for the “more on this later” part: It has to have to do with your unique situation - which the itch staff couldn’t diagnose to the degree you could. I would suggest the following approach: You, your IT, and your friends living in Switzerland should compare some specifications (browsers, recent updates to browser AddOns and/or OS, possible automatic updates to the router firmware). There has to be some sort of commonality. If you can’t figure out the culprit, present those commonalities either here or in an email to support (I would suggest here [“For Science!”] - but only if you would consider the information you want to present as not sensitive at all). Because that’s something they might be able to work with.
And now I’m going to say something really annoying: The issue might go away on its own and nobody will be any wiser afterwards. Don’t rebuy those 150+ games you own on another platform just yet. They might download smoothly in a week from now.