I actually love a childhood connection, but you're right, it really is so common it's almost a given. I wonder if part of the over-use is because it's kind of a "short cut" to feelings or chemistry. Because there's a built-in backstory, they get to skip the getting-to-know-you phase - aka fun flirting and developing tension - and go right to pining and unrequited love (and smut.)
If you don't read The Third Decade I highly recommend it - they meet and develop a whole-as adult relationship like actual humans. (They have had an encounter before, but briefly as adults, not a childhood thing.)
you hit the nail on the head on why the trope can be very tiring, it's because they skipped the flirting and tension phase when fun romance is all about that east Asians also go crazy with the fated trope, partners connected with a red thread or past lives they love when a couple have background connection to show they're meant to be as opposed to more westernized look of romance as "i chose you because to be with you."

can koreans stop being obsessed with childhood connection, the trope's always in most dramas or manhwas or bls. isn't it nicer to see their relationship developed as adults