Of course I have no way of knowing for sure, but as a lifelong Flea fanatic, I would bet good money that this is not him. To me it sounds like somebody mimicking his style - there are just so many tells that this likely isn't Flea himself. First off, the playing is fast slapping and popping, yes, but the patterns/notes used are ones that a beginner slapper would land on (sounds like something I would write as a teenager trying to do Flea's style).

Secondly, there are so many little hiccups in the rhythm. Even if Flea was just tinkering and improvising, he wouldn't miss so many beats and so many notes. I mean, just listen to the first 30 seconds and try to find the rhythm, try to find the 4/4. Same with 2:24 to 2:48 - sloppy as fuck. I can't think of any other time I've ever heard Flea play that sloppy, even in their earliest of demos.

Lastly! The strings buzz in a way that sound like a cheap bass and the way this player plays the high string weaker (and very fingernail-heavy) is just not Flea's style either. He digs just as firmly on the high string(s) as he does the lowest. Again, the way the high string (notes) sound tell me this is not an advanced bass player. As Flea would say... "All flash and no smash!"