I heard that the Wuhan Institute of Virology had inserted furin cleavage sites into random types of viruses in the past and that SARS-CoV-2 is unique among coronaviruses for having a furin cleavage site, but this[0] says otherwise:

``` Furin cleavage sites occurred independently for multiple times in the evolution of the coronavirus family, supporting the natural occurring hypothesis of SARS-CoV-2. ```

0: https://pubmed.ncbi.nlm.nih.gov/33340798/