I wouldn't have said it quite like >>1876
, but you shouldn't put any pictures in public places that you aren't comfortable with people keeping or spreading around. You have to relinquish some privacy to share your cosplay. If that worries you then you probably shouldn't do it.
As for getting traced, you'll be in cosplay and look a little different from your usual self, and how will people you don't know pick you out of a sea of billions with just a photo? Just don't upload the pictures anywhere with your name attached to them, or people can take your photo from here and reverse image search to see other places you've uploaded it, and get that info. Putting it somewhere like Facebook should be fine though because I don't think Google indexes Facebook photos.