"The Helvetii, a Celtic tribe who battled Julius Caesar, gave their name to the Swiss territory. The Latin name for the country, Helvetia, still appears on Swiss stamps. The letters CH appearing on Swiss cars and in internet addresses stand for the Latin words Confoederatio Helvetica, meaning Swiss Confederation."
It's not that .ch is a Swiss domain in particular, and more that I've seen websites with that suffix for years and just automatically assumed that they were Chinese, when in retrospect it didn't even make sense. Like, wow, all these Chinese websites are surprisingly anglo-friendly and the translations aren't messing with the layout at all.
https://en.m.wikipedia.org/wiki/.cn