While not everyone from the USA gets good download speeds, you clearly live in a prize location, well supported by GOG, who clearly show a bias, especially for many American customers or other popular customer locations.

Outside of those prime locations, GOG seem to be unwilling to spend any money on decent pipelines. It also appears, that around a year or so ago, they did some price cutting with certain servers, which is why I rarely get good speeds with them anymore, and even totally appalling ones during big sales. But you also need to consider, that a constant 204 KB/s for 24 hours a day during a big sale, shows a deliberate limiting going on. If it was just pipeline issues, the speed would vary, especially at different times in the day.

So lucky you, count your blessings ... especially with what I can only describe as an amazing download speed ... if we could all be so blessed. I count it a good day, when I can download 1 Gb in 10 minutes ... pretty rare for me now ... with GOG.

I have a 50 Mbs connection (roughly 5 MB/s). Be nice if I could get anywhere near that with GOG now ... I used to, and nothing has changed my end that I can tell ... everywhere else I download from is still about the same good speed.

I doubt they are throttling you then ... and you are one of the lucky ones ... and must be in a prime location.
Many of us would be happy to get a quarter of the speed you are getting ... I only get that quarter on a very rare good day.

There is a huge disparity between 204 KBytes / second and 18 MBytes / second. It is like the difference between the Haves and Havenots.

204 KBytes/sec is very bad indeed.
On business trips I downloaded GOG files from various locations and never had anything like that. Also my friends (also in other countries) don't have that problem.
Actually I haven't seen all that many people complain about download speed, so I'd rather say there are some unlucky ones.

Try to get the location (or at least the country) of your GOG download server, then run a speedtest.net to a server in that area, see if that is slow as well.