I have not seen much recent material on the lab origin of SARS-CoV-2, our beloved Covid-19, the interest has gone a bit cold with on-going tyranny taking centre stage. Still, here is interesting material, somewhat technical, discussing the significance of the furin-cleavage sites on the Covid virus. Influenza viruses do not normally have this, it is said, so something odd must have gone on, via gain-of-function engineering.
https://harvard2thebighouse.substack.com/p/a-grin-without-a-cat