Haven't heard anything about LLC capitalization in this context. Liability shield can be pierced, but only if LLC is misused (i.e. "when the company is treated as a personal "alter ego" and used to commit fraud, injustice, or illegal acts"). Lack of capitalization is not one of the reasons as long as you treat it as a company, not your wallet.

No there’s lots of reasons it can’t be pierced. It doesn’t shield you from liability that results from your own negligence, and for owner operator businesses that’s a large attack surface.