/lib/udev/rules.d/69-xorg-vmmouse.rules is in xserver-xorg-input-vmmouse 1:12.8.0-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 | ACTION=="add|change", ENV{ID_INPUT_MOUSE}=="?*", ATTRS{description}=="i8042 AUX port", KERNEL=="mouse[0-9]*", PROGRAM="/bin/vmmouse_detect", ENV{ID_INPUT.tags}="vmmouse"
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