As a parent in the thick of babies exactly at this age and surrounded by other parents in the same situation, I cannot tell the difference between a "covid" baby and any other.

What I can tell you is how much time and effort the parents are putting into the baby, and whether is home-schooled or goes to school/daycare.

First child? They're probably walking early. Third kid? They'll be pushing a year and a half old with barely 5 words in their repertoire and I'll consider them lucky if they can hold themselves upright using a chair for support.

The parents with 3 young kids just don't have the bandwidth to provide the kind of attention that the baby needs.

I essentially think about it this way - consider how much information AlphaGo has to learn with. Now consider how much information your brain processes with only your vision. You think there's gonna be a statistically relevant causation because there's a piece of fabric on the adult's face?

I can't say for certain, but from my daily sampling it's much less than you intuitively would think. Kids are resilient and motivated to learn.