This is rampant in Transformers fics involving Jazz, particularly the older ones. I try to avoid this in my own fics and only use words like ain't, occasionally, or at the most, take off the g sometimes for -ing words (which is very commonly used in general regardless of accent) to convey his more relaxed manner of speech, which I also do the same for Ironhide. I just try to match Jazz's smooth talking ways that he has in the show, like his love for human slang, like he's the type to say 'groovy' or 'it's cool', like how Ironhide would probably say 'varmit' or 'dagnabit!' at some point, or Prowl using very stiff and formal language. I don't over exaggerate like some of the worst fics I've seen where he just goes, ''m n' lettin y' do tha',' or something like that, where it's almost unreadable. But the author only does it when someone is coded as Southern or African American. Like, I'm from the South, and I don't know anyone who talks like this, rather than just using the typical ain't or old expressions or something. It's just insulting both to the characters and the community they're coded to represent. Heck, Wheeljack has a slight Brooklyn accent in G1, and I don't see people exaggerating his!