There is an updated pull request by traeak against master on the void-packages repository

https://github.com/traeak/void-packages rtl8812au-dkms-20210820_6
https://github.com/void-linux/void-packages/pull/51054

rtl8812au-dkms update to 20210820_1
Allows building with 6.9.x

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#### Testing the changes
- I tested the changes in this PR: YES

Built and installed on my machine with 6.9.7_1, plugged in dongle and wifi worked.
copied package to another machine on network with 6.9.6_1, installed.  driver loaded but didn't associate with a station, rebooted to 6.9.7_1 and automatically initialized and connected.

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#### New package
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#### Local build testing
- I built this PR locally for my native architecture, (ARCH-LIBC)
- I built this PR locally for these architectures (if supported. mark crossbuilds):
  - x86_64


A patch file from https://github.com/void-linux/void-packages/pull/51054.patch is attached