This is not a SFW instance. NSFW communities will be tagged, and efforts will be made to keep SFW communities clean, but proceed at your own comfort level.
From what I know, it has to do with the word red covering the purple part of the spectrum long ago, and the “need” for the word purple came out later but purple things that were named red didn’t get renamed.
You can look at japanese right now and 青い covers both blue and green, with a relatively recent addition of 緑 to cover only green (thus possibly pushing 青い in the future to be only blue, who knows)
From what I know, it has to do with the word red covering the purple part of the spectrum long ago, and the “need” for the word purple came out later but purple things that were named red didn’t get renamed.
You can look at japanese right now and 青い covers both blue and green, with a relatively recent addition of 緑 to cover only green (thus possibly pushing 青い in the future to be only blue, who knows)