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In any case, it feels like the cause of a Newbie Boom, so it could be listed there. (That's Trivia instead of YMMV, but captures the "X causes Y work to gain a new audience")
Unfortunately, these are not the answers.
I remember one example given was that somehow, My Immortal caused tons of people to be interested in Harry Potter. I'm not a Harry Potter fan but that example sticked out to me because of how infamous My Immortal is
This could all just be me misremembering things but I don't think so
Edited by TankEngine75RealI scanned through the YMMV and Trivia pages of My Immortal, but didn't see anything like that there. Could have been a page that was never cross-wicked, cut, or, yeah, misremembering.
Like I said, a fanwork that causes readers to go check out the original work is an example of causing a Newbie Boom, even if that isn't exactly what you were looking for. Could still be an option to capture it.

Examples include: 1: Thanks to the popularity of (FANFIC NAME), many people began to check out the (ORIGINAL WORK) 2: A game mod that adds stuff from (ORIGINAL WORK) to (NAME OF GAME) gets popular to the point where many people began to check out the (ORIGINAL WORK) 3: A massive multiplayer crossover fanfic gets popular and people check out all the works they've never heard off that were featured in that crossover
I don't think it is Colbert Bump nor Parody Displacement as i remember reading a YMMV page like this and remembered some examples (those examples do not appear in Colbert Bump nor Parody Displacement)