It is a myth.
We might have our own preferences, one person can state that they prefer an Earth with no more than 5 billion, or 3 billion. There are probably people out there that would prefer zero humans, or that they be the only people on Earth.
But those remain as personal preferences, nothing more.
The objective reality is that the Earth can never be overpopulated
By definition, there can be no more people on this planet than God actively chooses to ensoul.
There are some things that God allows to happen, but has no active part in. Sin is an example.
But that cannot be true for the creation of a human. It is not something that God simply allows to happen, but one that God must have an active part in. A human couple cannot create a new soul. Only God can do that.
Therefore, every single human born is a human that God actively desired and actively created.
So, by definition then, the number of humans on the plant is the number that God desires. Even then the number is LESS than God desires, as God does not desire that babies be aborted or anyone be murdered.
So no, there can not be any such thing as ‘overpopulation’.