The Wu and Zhao paper [0] you cited is based on this paper [1] by Zhou et al, whose conclusions were questioned by this preprint [2].
In fact, the paper [3] cited in the top comment has the following response to the Wu and Zhao paper you cited:
> The recent acquisition of the FCS by SARS-CoV-2 via a natural insert was proposed by Wu and Zhao (2021) on the basis of the existence of FCS in other, more distant Betacoronaviruses with different loop positions to SARS-CoV-2 and the existence of a partial natural insert in the same region in RmYN02 (Zhou et al. 2020a). The reliability of the conclusions of Zhou et al. (2020a) has been questioned by Deigin and Segreto (2020), who particularly challenge the claim that RmYN02 has an insertion around the site of the FCS insertion in SARS-CoV-2 and instead point to a two amino acid deletion in RmYN02 at that locus. Therefore, RmYN02 should not be used as evidence of the natural origin of SARS-CoV-2′s FCS until its claimed insertion is properly validated.
In fact, the paper [3] cited in the top comment has the following response to the Wu and Zhao paper you cited:
> The recent acquisition of the FCS by SARS-CoV-2 via a natural insert was proposed by Wu and Zhao (2021) on the basis of the existence of FCS in other, more distant Betacoronaviruses with different loop positions to SARS-CoV-2 and the existence of a partial natural insert in the same region in RmYN02 (Zhou et al. 2020a). The reliability of the conclusions of Zhou et al. (2020a) has been questioned by Deigin and Segreto (2020), who particularly challenge the claim that RmYN02 has an insertion around the site of the FCS insertion in SARS-CoV-2 and instead point to a two amino acid deletion in RmYN02 at that locus. Therefore, RmYN02 should not be used as evidence of the natural origin of SARS-CoV-2′s FCS until its claimed insertion is properly validated.
Disclaimer: I’m no biologist/virologist.
[0] https://www.sciencedirect.com/science/article/pii/S187350612...
[1] https://doi.org/10.1016/j.cub.2020.05.023
[2] https://arxiv.org/abs/2012.00627
[3] https://link.springer.com/article/10.1007/s10311-021-01211-0