not that complicated
its based on this "meme" about how much you care about a seemingly unimportant thing, which is depicted by contrasting a guy with a suit vs a guy with casual clothes, for example for the endgame premier the guy shows up with a suit and for his marriage he shows up with shorts, thats suppossed to be funny
Then someone thought it would be even funnier to apply that logic to things no one really cares about, for example Morbius, the problem was that most people dont know what a "morbius" is, so they couldnt join in on the fun.
The first joke was about showing how much you cared about something and ironically saying it was more important than for example your marriage, now the joke has changed to be even more ironic and its about saying look at me saying how much I care about this thing I clearly dont care about
This has also mixed with a recent joke of though looking guys with suits being excited for something that is either seen as childish or girly, this happens because the contrast is really funny and/or also because there might be things in that childish/girly "thing" that really does excite people who are outside of the usual target audience
Someone applied the same logic minions 2, but because everyone knows the minions, because theyre seen as uncool (and thus ripe for ironic jokes) and because theres some nostalgia there, the meme spread and it became a tiktok trend (I think), however most of the people doing it are tik-tok teens who havent thought much about it and are only copying it because its now a trend (and therefore cool), while also being a pretty harmless way to have some fun.