Why it was artificial:

From peer-reviewed articles before 2020, we already know that similar virus samples were created via gain-of-function and RNA-printing. A whistleblower has come forward and has explained exactly how it was made.

According to the labs, the virus is a chimera (artificial combination of at least 2 maybe 3 viruses). It has an unatural RxxR cleavage site that make it 100x more viral. It was fully adapted to humans and not to animals (incl bats).
And before the mutations (which happen daily), the virus codes were identical to those known in the labs.

The counter arguments are absent, use the appeal to nature fallacy. And from leaked e-mails we know that scientists in the field were pushed to claim it was natural before any research was done. Often these scientists have done gain-of-function research.