The common blood moon theme is that everyone gets a mask....

Does Jhin replace his mask or get another one?

Also considering that Jhin says 'behind the mask is another mask', that would mean he already was wearing two masks. Is blood moon his 3rd mask?

Finally there's a saying (at least where I'm from) where 'the face masks ones true self'. If we take that into account, does BMJ have 4 masks?!

We must know whether BMJ has 4 masks, for the sake of perfection.