Emulator

The locale defines the thousands separator as the single character \xA0 (NO-BREAK SPACE).
We assume the fmt::format result can be interpreted as a utf-8 sequence but unfortunately NO-BREAK SPACE is represented as \xC2\xA0 in utf-8.
\xA0 is just invalid in utf-8.

There is probably more code that assumes fmt::format produces valid utf-8 sequences. Numbers and strings will have to be handled separately? 🙁

I've got the same problem in 5.0-21088 when Windows 11's system language is nb-NO, as Norway's official number formatting uses a space to separate thousands (resulting in, for example, "1 037,41 MB"), as well as commas for decimals, like the Polish screenshot in the OP.

I wonder if it'd be possible to simply replace "No-break space" with a standard "Space" in Dolphin's code for situations like these; I give 40:60 that I'd be able to submit a pull request for it.

DandelionSprout wrote in #note-3:

I wonder if it'd be possible to simply replace "No-break space" with a standard "Space" in Dolphin's code for situations like these; I give 40:60 that I'd be able to submit a pull request for it.

It's easy enough to replace ASCII NO-BREAK SPACE with UTF-8 NO-BREAK SPACE to fix just the number formatting in question, but that's not necessarily the cleanest fix. Potentially other locales have similar problems with other characters, and potentially in other places in dolphin. Ideally we'd have a more generic fix to deal with all of our formatted strings being assumed as valid UTF-8.

I wonder if it'd be possible to simply replace "No-break space" with a standard "Space" in Dolphin's code for situations like these; I give 40:60 that I'd be able to submit a pull request for it.

The no-break space isn't defined in Dolphin's code, it's defined in the locale.