It's been "fixed" more than once. And it looks like it may be in need of fixing again.
The Language section can provide an indication of whether a certain region is getting polled to a greater extent than usual, and sure enough, we see the percentage of Windows systems running "Simplified Chinese" has skyrocketed from the previous month, going from 23.58% of systems in July up to 31.04% in August. Those 7.46 percentage points means the relative share of systems running that language has supposedly increased by nearly a third from one month to the next.
Korean systems also skyrocketed according to the data, going from 1.75% in July up to 3.04% in August. Though interestingly, their share in July had been more than cut in half compared to June, so perhaps Valve performed a correction then, only to have their fix break again the following month. Both countries have a large number of net cafes, which suggests there may once again be issues related to those.
The big change in the demographic has undoubtedly skewed results across the survey. Just look at the Windows version data as a good example. Windows 7 64-bit inexplicably climbed from 5.68% up to 9.00% between the July and August surveys. And back in the May survey, the OS accounted for only 2.04% of systems, with Windows 10 at 96.56%. So, over the course of just three months, Windows 7 64-bit's usage share has supposedly increased to over four times what it had been.
While the Steam survey can have some usefulness in showing trends over longer periods of time, it's probably not a good way to analyze short-term changes. It really needs a major overhaul to be more useful, such as by allowing data to be filtered to specific regions and other criteria.
That being said, I do suspect Nividia's share of graphics card sales relative to AMD is currently higher than usual. Nvidia is mostly just making graphics hardware on the 10nm node, whereas AMD needs to divide its 7nm production between CPUs, GPUs and console APUs. They are contractually obligated to make tens of millions of large console chips for Microsoft and Sony, and when it comes to deciding whether to dedicate the rest of their capacity to CPUs or GPUs, the CPUs are undoubtedly far more profitable on a per-wafer basis. So, only a relatively small portion of their production has likely going toward graphics card chips.