I noticed that a lot in movies/tv shows they act like its either straight or gay and bi people don't exist. Sometimes they even wrongly call people who would actually be bisexual gay by accident simply cause at the time they are dating someone the same gender. Maybe its ignorance or not being up to date with the specifics. Or maybe they do it to get woke points. Like you mentioned Jackson then there's other characters from another show for instance {just to prove my point} is Kathryn from Desperate Housewives was called a lesbian despite having 3 male romantic partners and only 1 female partner. She's clearly bi. Cannonically bi in everything but the creators words/script. Or Clawdeen from Monster High, in some episodes and even movies she's shown interest in boys sure not as much as her friends but there's still signs {such as blushing} yet the show creators say she's a lesbian despite never showing interest in girls. Again that's clearly bi. I know you might not know these shows/franchises but they were just examples to how it seems shows/films call a character gay or straight based on who they are currently dating rather than just their actual sexuality.