>>What is the correct population to have?<<
It’s not a question of “correct population” but rather “sufficient numbers of educated, skilled, productive people to keep civilization going”.
Once you fall below a critical number of those people (and I think our “supply chain” issues are a symptom of that) then things fall apart: too many consumers of stuff, not enough skilled producers.
Well, all of this touches on the individual reproductive choices which literally billions of women are making for their lives.