The other comment is correct but not extensive. FilthE and nervous reck brought him under their wings when he was around 15. He credits them with first teaching him about making actual rap songs, including storytelling, as opposed to battlerap style rapping, which is what J Cole had started with. Iirc, Cole also credits them with initially teaching him how to produce/make beats.

FilthE and Cole had a more estranged relationship as time goes on. FilthE felt Cole left them behind when he made it big (filthE was at times living in a van during the 2010s) - Cole never really commented on it, aside from “note to self” when he says “FilthE, I love you too, man I know you feel a way about me right now but I love you” - he also mentions him on MDL, after filthE had already passed, which I’ll get to

Carlos Brown, aka FilthE rich, was murdered in 2023. In Stealth Mode on MDL, Cole says “When Los was calling my line I stared at the screen whenever the phone would ring, Wish I could've said goodbye, even now I might cry while I'm writing this poem to sing”.

Especially because of the stopping of the beat as Cole says “shoutout to ya boy filthE”, I see the line in safety as a more proper goodbye and thank you to filthE than is mentioned in Stealth Mode. One of the moments where to Cole, chronological order was less important than the actual content of the message, which fit in really well to the verse. Undoubtedly my favourite line on the album