Spacers on both sides are identical and the wheel is centered
If it's centred between the dropouts, it might not be centred between the brake posts. The position tolerance when they were welded on probably wasn't super tight, and it doesn't take much to throw the angle off to a noticeable extent.
Cross post from my cp thread
Can anyone point me to the reason why the right mini-v arm has a different angle than the left one when the brake pads touch the rim?
Spacers on both sides are identical and the wheel is centered, too
Many thanks