Fading Leaves - Pilea peperomioides

WHY DOES THIS HAPPEN
As a result of receiving too little fertilizer, Chinese money plants (or Pilea peperomioides) can begin to lose their rich green color and instead fade to a lighter green or yellow color.
It may also be possible that it isn’t the amount of fertilizer that is the problem, but the type of fertilizer itself. These plants can sometimes be a little bit sensitive, so you should make sure to use a fertilizer that is suited to green plants specifically.
Always also make sure to dilute your liquid fertilizer in water correctly - if the solution is too strong, you can damage your plant, i.e. by burning its roots. Something to bear in mind is that it’s much easier to revive an underfertilized plant than an overfertilized one, so while it may be tempting to try to balance out a nutrient deficiency by applying large amounts of fertilizer to your Pilea, this will do more harm than good.

SYMPTOMS
It’s possible that your Pilea will also start to show other signs of underfertilization, such as:
General weakening of the plant - leaving it more susceptible to disease and pest infestations
Stunted and/or irregular growth
However, note that chlorosis (yellowing of the leaves) is the most common characteristic symptom of this problem.