If this is one of ours it would be the John Brown isekai meme:
Since we’re time travelling. Gotta hook our boy up.
If you wanna see a web comic that actively calls out this kinda shit, I can’t recommend ‘This Isekai Maid is Starting a Union’ enough.
And if you wanna see the complete opposite, try subjecting yourself to Kuma Kuma Bear, the whole thing is just the author’s neoliberal power trip. It hasn’t gotten to the point of slavery (yet) but apparently child labor is fair game and God really loves you only if you accumulate wealth.
Is this actually that common of a thing? I try to stay away from the trash side of anime, which is to say a solid majority of it nowadays and especially anything that could be described with the word harem, but I struggle to accept the apparent reality that slave romances are a common trope in the genre. Like that’s straight against the wall, do not pass go, do not collect $200 kind of behavior and to think that that has such an audience that it’s become a staple of the genre is maddening. In the lovecraftian sense
The Rising of the Shield Hero was the very popular show that had this trope, but there are some others.
Also that Ancient Magus Bride one came out nearly the same time.
Eeeeeeh Ancient Magus Bride is playing with slightly problematic tropes but it’s a show about found family and overcoming trauma, it’s more in the ball park of Beauty and the Beast than cryptofash wish fulfillment bull like shield hero