What is the logic behind which SUBGENRES that will show on top of title page alongside with GENRES?

Hello. On the movie "The Hook" https://www.imdb.com/title/tt29204860 I added on #250929-185820-806000 Genre: Music then after on #250929-190113-201000 I added subgenre: rock-music But the "rock-music" is only listed among the Keywords down on the page. It is not "on top" alongside the other genres/subgenres. I also added subgenre: dark-comedy #250929-185034-766000 But that subgenre did also end up on topp of the page. Is there a logic here to which subgenres that will be showing on top, and which will only show as a "keyword" down on the page? Or is there an error/fault her in the system? Did not find any info about it here: https://help.imdb.com/article/contribution/titles/keywords/GXQ22G5Y72TH8MJ5#subgenres