The first to point this out, in February 2020, was the Wuhan Institute of Virology:
https://link.springer.com/content/pdf/10.1007/s12250-020-002...
This strange furin cleave site allows the virus to bind to human ACE2 receptors. An interesting scientific reading on this, which does not rule out genetic manipulation in a lab:
https://onlinelibrary.wiley.com/doi/pdf/10.1002/bies.2020002...
https://www.sciencedirect.com/science/article/pii/S187350612...
HCoV-OC43 and HCoV-UK1 both have them and they've likely evolved several times over in parallel evolution (or as the result of multiple infection and recombination maybe?)
It is almost as if Sarbecovirus acquired portions of the Hipposideros genome. You'll note your article also says this did not come from pangolins or its closest bat relatives, which shoots down another media narrative.
> Strains of SARS-CoV-2 (we also added sequences from the GISAID database) have furin cleavage sites at spike S1/S2. Moreover, SARS-CoV-2 is the only virus in subgenus Sarbecovirus having this feature, while even its closest relatives, bat coronavirus RaTG13 (sequence identity 97.7%) and pangolin coronaviruses (92.9%–90.7%), do not have furin site.