Hi! Author here. I added a http → https redirect to my book website, thanks all. I do intend to always serve public content via https to (as other smart folks have thoughtfully mentioned) guard against stuff getting messed with between my server and your browser (however unlikely that may be). In this case I thought my server was redirecting to https, but turns out my Firefox was forcing https (again, same as other smart folks said).
re: "expert", ugh, I'm embarrassed to even use that word, but someone else graciously called me that (so I intended to remove "self-proclaimed"), and it supposedly helps for sales. All I know is I'm growing and learning just like you, the more I know the less I know I know, and I make mistakes all the time. I always appreciate kind corrections/feedback/comments/patches/suggestions/etc.
That includes feedback on https://github.com/meonkeys/shb/blob/main/pelican/website/content/extra/.htaccess ... I feel clever fixing two things in a single redirect (getting rid of www. and forcing https), but I'm not sure if I'm doing something silly or dangerous here. I'm definitely not an expert at Apache mod_rewrite, I just cobbled that together from official docs and stackoverflow posts.