I don't know what source you're getting that from but novelupdates.com, reddit, mangaupdates.com, webnovel.com, and Google says it's not an mpreg and is just a dark fantasy. Even the author hasn't put a mpreg tag on it, I think it's safe to assume that the source you found isn't the most reliable. Try looking it up under the name "Tales of an Obscene scholar" or it's official name "Omran Seonbi-yeon", You could even use the alternative name 음란선비뎐. I'm not defending this trashy manga, but I can guarantee it's not mpreg.
(unrelated) I think it has something to do with certain Asian cultures finding adoption to be wrong so when it comes to BL adoption is a no no but getting a man pregnant and having him pop babies out his rear is ok ig, which is honestly insane. I totally agree with you, mpreg is pretty out there. Wish they would just stick with adoption and pregnancy tropes. Ngl tho, some abo stories are just 'chefs kiss' (づ ̄ ³ ̄)づ ╮( ̄▽ ̄)╭

Mpreg is not for me. Dropping it.