Certainly during the WWII era camouflage was developed by people with normal color vision to fool other people with normal color vision. Because colorblind people literally see it differently it doesn’t fool them. (At least, it didn’t - I have no idea if modern camouflage takes this sort of thing into account.) This is not just because of the color differences, it’s also because the colorblind tend to pay more attention to texture and outline than those with normal color vision.
Where colorblind “spotters” were used most was in analyzing color photographs (rare and very expensive back then, but the military did use color photography). If they went along on a flight it would be in an attempt to spot something under something like camouflage netting or the like.
There were apparently colorblind snipers as well. Again, they were less likely to be fooled by camo and more likely to spot enemy soldiers hiding in bushes and the like.
This is also affected by the type of color deficiency. People who were truly red/green blind, who only had two working types of cone cells rather than three, were much better at seeing through camouflage than people who were “color weak” with a partially functioning third cone. Red/green colorblindness worked better for spotting people and stuff in foliage, or for spotting khaki camo. I don’t know if there were special roles for blue/yellow colorblindness, which is less common and not sex-linked, or how that would have worked out.
If anything, they’re more likely to take someone with “color deficiency” these days than back in WWII. My understanding is that back in WWII the ban on color-variant pilots was absolute.
My deuteranomaly did not pose a bar to me getting my civilian pilot’s license… in the US. There are other countries that not only bar the colorblind from flying as pilots, they also bar them from getting driver’s licenses as well.