I believe I've identified a bug introduced during the equipment customization update (1.2) which has so far gone unnoticed.
In this update the default equipment colours for both Security and Insurgents were changed from a Sand otherwise yellow-ish colour to Tan for Security and from the old shade of Black to a darker Black for Insurgents.
However, if you create a brand new profile in the game (or nuke your existing profile and cosmetic data files) the default equipment colours are set to their pre-1.2 update defaults and when you go into the customisation menu Tan and the new shade of Black are not selected.
I believe this also leads to a further issue in-game where players who haven't customised their equipment loadouts appear to have mismatched gear (brown vest and sand backpack, black vest and "lighter" black backpack) which doesn't reflect the original (pre 1.2), default equipment colours or the new darker Black and Tan.
Here are some screenshots outlining the issue.
Freshly nuked profile showing the default equipment colours for security
Vest customisation menu showing Tan unselected by default, I don't even own the Sand coloured gear which is currently equipped.
Correct appearance of Tan
Insurgent customisation screen showing new black on the vest and old black on the backpack.
Players in-game to the far left and right showing mismatched gear for security (also noodle arms).