That's true Delta leaked in Taiwan, but that was a preexisting natural strain. Smallpox's last fatality also was a lab leak. However, most gain of function experiments use test harasses that can't infect humans or can't replicate. It's not impossible, but it's hard to have any conclusion at all at this early date with very little evidence.

The virus is infecting so many people and changes so rapidly that a natural explanation will not be surprising in the least. New variants have been expected. I think people are surprised at how bad the new variants have been, but anyone following the scientific literature wouldn't be taken completely off guard.