Harry Enten: "Whatever he is doing with independents, it ain't working. They despise him at this point!"

[ProfessorGAC]

4. Not Quite

Yes, one has to ge below 50% but underwater means the difference between approve & disapprove us a negative numer.
That would be impossible if approval was 50% or higher.
In most polls there is some percentage of "not sure" or "neutral". So, approve + disapprove does not always add up to 100%.
That pushes down the maximum the "approve" can be.
In the case of the Faux poll, it may be something like 55% disapprove, 38% approve, 7% undecided.
But, the underwater here is 38 - 55 = -17%. (Again, the numbers are just for example.)
For someone just elected 383 days ago, it's pretty dreadful.