In installing and utilizing cURL (specifically curl 7.86.0 (Windows) libcurl/7.86.0; previously I said it was curl 7.83.1 (Windows) libcurl/7.83.1 but I was mistaken) to download .htm files in conjunction with/subordinate to a mass media-file downloading program called gallery-dl, I ran into a filenaming problem regarding how cURL deals with "weird" characters.
Basically, it seems that at least for my version or install of cURL, when I try to use some kind of alternate version of a symbol such as Big Solidus ⧸ slash instead of normal slash in the filenaming command, cURL will create the .htm file but will replace that alternate symbol with an underscore.  I know this isn't a problem with cURL interpreting the Big Solidus as a normal slash, since when I try to instead use a Fullwidth Solidus ／ slash it errors out the same way it would with a normal / slash.
As a simple example, try running something like curl [url] -o C:\dir\ec\to\ry\test⧸.htm or curl [url] -o "test⧸.htm" yourself.  For me, it outputs test_.htm.
Is there anything I can do, anything I can attach to the "weird" characters to get cURL to avoid changing them to underscores?  Or is this something version-related?
Ok, so OP here, and I've since seemed to figure out a solution to this problem, although the actual nature of the solution I'm not really certain of.  It was seeming like Linux versions of cURL were not having this problem of changing characters like alternate versions of functional characters (and other characters I had since discovered mine was also changing, like Japanese characters) into underscores, while multiple Windows versions were.
My friend decided to compile a Windows build of cURL himself from the current source code available on github to run a debugger, and for some reason this version just doesn't have the changing-"odd"-characters-to-underscores problem?  It just.... doesn't have the problem at all.  You ask it to create a file with Big Solidus ⧸ or a Japanese character あ or anything like that and it does it just fine.
Our only guess is that it's down to a matter of slight differences created by different compilers, and the compiler used on the official Windows builds creates the problem while some other compilers don't.
cURL automatically replacing alternates to functional characters with underscore?