What you’re seeing is apparently normal when there isn’t enough ambient light for “color night vision” on the v3, but it hasn’t switched to night/IR mode. There was another thread where people saw similar, it seems to vary in intensity from cam to cam. Try changing the night vision conditions to “dusk” (if the v3 has that option) so it comes on sooner, and leave the night vision mode on “Auto”.
You can test this by leaving night mode “off” then turning on a light in the garage. The purple hue should go away completely.
I’ll see if I can find the other thread.
EDIT - Here is the thread. It is long but you can see the same effect (gets more extreme the darker it gets). This person seemed to notice it was worse on one batch of cams than another, and it seems to have started with a firmware update. The basic result is that you need to make it switch to night mode (IR) before it gets too dark.