Recently, someone removed Invincible (series) from the vast majority of Think Mark Think! (meme) and someone updated a majority of Sad Cat Dance (meme) to be both Chainsaw Man and Higashiyama Kobeni. And then not even 3% of Jack-o' Challenge is tagged Guilty Gear, much less the origin character.
So this is to say that there's flat out no standard practice when it comes to tagging memes with their origin series or character and that I think it would be beneficial to have a semi-solid way of this.
I believe that memes should be tagged with their origin copyright when it's a very obvious scene reference with an obvious copyright, such as the Mark meme just mentioned. I further believe that they should not be tagged with the relevant characters without obvious cosplay. Past that, I'm honestly not certain. And, frankly, I'm not too strong in my first stance...