Pretty sure masks were commonly worn in Japan before Covid, and continue to be worn after Covid. You can actually see quite a lot of manga or anime characters that incorporate it into their design; as for Honjou, I associated it with her due to the cover, and as I said, it does fit her personality to wear one, to hide her face, not unlike how she wears a baggy hoodie to hide her body. If I've reached this conclusion about her personality, it is within reason that Shirasawa could too.Irrelevant. Like I said, she doesn't wear a mask in the manga. This is just art that must have been inspired by the COVID-19 pandemic.
It's a meaningless hypothetical, because the issue you're focusing on is meaningless. Shirasawa could've come up with any number of explanations in his head as to why she's wearing a mask - if the mangaka did consider it an impertinent matter for the audience, she could've easily written it away with a simple, single panel conversation like that. If it can be explained away in such a simple way, it's hyperbolic to suggest it's some big plot hole in the interaction here.If the author had done this I wouldn't be complaining in the first place, but she didn't. I don't see the point of this hypothetical.