"Often has a dangerously different osmolality. Infants eat whatever they are given and have dumb kidneys, so are prone to hyponatremia or hypernatremia and every pediatrician has seen a baby die this way. Don’t do it."

See that and other discussions here about the differences between infant (above) and toddler formula.

That makes sense, but again, for anyone who has ever taken a chemistry class, creating a solution with a known osmolality is not difficult - basically all you need is a scale. But I also don't doubt that rando TikTok recipes are wildly dangerous.

And the age range argument doesn't really make sense if there were a standard recipe for "human breast milk replacement". I'm pretty sure human breast milk doesn't change composition as a child ages, and no one is arguing you can't breast feed toddlers because the milk is for the wrong age.