You might get differing answers due to the payment portion of the scenario, but here’s my 2 cents.
No, there’s nothing morally wrong here at any level to me. This is legally ok as far as the ages go, pretty much everywhere.
As long as there’s no power dynamic being abused, and both sides are consenting, go for it.
Check the roots, you might have pests eating the roots. Could also be too much watering. Hard to say from photos but I definitely think something is wrong below the surface