BUR #3937 has been rejected.
create implication tan -> dark_skin
This has been discussed in the past (topic #17512) and came up on Discord again when discussing Libeccio
As it stands now the distinction between tan and dark skin is entirely arbitrary. Currently the definition for dark skin is "Skin that is darker in tone than the usual Caucasian/East Asian skintone." and the wiki also states that "Characters usually have this skintone naturally, but sometimes have dark skin due to a tan", meanwhile the only definition for tan is "Skin darkened due to exposure to the sun.", which means that sans the presence of tanlines it's virtually impossible to tell them apart unless you happen to know the natural skin color of the character, and even then it should be tagged with dark_skin since 1. They would have darker sking, making it dark skin by definition and 2. The current criteria for dark skin allowing tanned skin as well
IMO, the tan tag should be used exclusively for when tanlines are visible or for when a character is canonically light-skinned, and even then if you wanted to look for tanned images of a particular character you could easily just search for character+tanline or character+dark_skin, making tan completely redundant, but you could make an argument that nuking tan completely would make it harder to search for characters with natural dark skin.