Source: https://linux-hardware.org/?view=os_display_server
Reporting is done by users who voluntarily upload their system specs via
# hw-probe -all -upload
I imagine people who care about this sort of thing are more likely to report it. And people who care about this sort of thing are also more likely to be early adopters and go through the effort of switching to Wayland.
The way to get a more random sample is not something I want (built-in, automatic telemetry by default). So I'm fine with having skewed data for something like this.