How was the reaction to J-POP in the 80s and 90s?

‌I was watching 90s Korean pop songs on YouTube and happened to come across some J-POP
The songs are so good
Besides RUN, I LOVE YOU, 17-sai, YOUR MY SUNSHINE, and Oh My Juliet,
there are so many great tracks. Above all, the melodies are wonderful
The female singers are pretty too. Is that Chisato who sang 17-sai?
But I'm seeing songs that are similar to or identical to Korean songs. Is it plagiarism?