For many years the XOR sprite cursor was patented, but the patent seems to have expired in 2013. One of us should make the request to the GNOME/KDE/Wayland/DE people and link the expired patent:
EDIT: The linked patent seems to only cover 1 bit inversion, not full color inversion. I can't find the patent for the full color, but recall reading that a patent stopped the adoption of a nice color inverting cursor for Linux that Windows has had for so long. If Windows has had it for as long as you say, then perhaps any relevant patents have expired?
That patent is only for MSB XOR though and seems to be only for hardware. That's not the only way to do it if someone wanted to achieve the result of better visibility.
https://patents.google.com/patent/US5471570A/en
EDIT: The linked patent seems to only cover 1 bit inversion, not full color inversion. I can't find the patent for the full color, but recall reading that a patent stopped the adoption of a nice color inverting cursor for Linux that Windows has had for so long. If Windows has had it for as long as you say, then perhaps any relevant patents have expired?