The thing about this l-carnitine craze, is that people who push their over-priced bottles, have a reason to tell you that it is amazing and will change everything. In my experience, it is nothing worth taking, and even if it did something, you wouldn't know it was doing it.
If you ask any real pro, whether it be Fouad's entire podcast or others, none of them take it, and those who have tried, experienced nothing from it. Jay Culter and those from the 2000's never took it, so bodybuilders have been getting shredded without it this entire time, but Chase Irons and others like him, have a vested interest to sell their over-priced L-Carnitine. If you know how cheap it is to make, everyone selling it is raping everyone buying it. No one should be buying it from anyone, and should be brewing it themselves. I know John Meadows was a proponent of taking 200mg per day for heart health, but how would anyone know that it is working? My one friend who is an IFBB pro, also does 200mg per day for the very same reasons, but never said he uses it for fat burner. I know a few others who take oral l-carnitine, but we know its utterly worthless unless you're taking 4grams a day. Point is, you can get lean without it.
But to blast 1-2g for "fat burning" purposes, especially if you're not brewing it yourself, is asking to get ass-raped by all these "influencers" trying to make money, and you'll see it is absolutely not worth it at all. Even if it did something, it would be minimal at best, and there is nothing magic about it that would prevent fat gain or increase fat loss, as all it supposedly does is help mobilize fat; thus, there is no mechanism for one to prevent getting fat on a bulk, or lose fat on a cut, if they aren't in a deficit
And finally, turning yourself into a pin cushion ED, injecting 3ml of it per day, 6ml if you're doing 2g, is not worth it, in of itself.