> How is that wrong? Not sure where, how or if it's defined as part of Unicode, but so far I assumed that for a Unicode grapheme there exists a notion of what the visual representation should look like. If Unicode still defines capital of ß as SS that's an error in Unicode due to slow adaption of the changes in the German language.
In unicode the default is still SS [1] while the Germans seem to have changed it to ẞ [2]. That means now it's the same on every system, but once the unicode standard changes and some systems get updated and others not there will be different behavior of len("ß".upper()) around.
I don't know how or if systems deal with this, but ß should be printed as ss if ß is unavailable in the font. It's possible this is completely up to the user.
[1] https://unicode.org/faq/casemap_charprop.html [2] https://www.rechtschreibrat.com/DOX/RfdR_Amtliches-Regelwerk...
"ß as SS that's an error in Unicode"
It's not. Uppercase of ß has always been SS.
Before we had a separate codepoint in Unicode this caused problems with round-tripping between upper and lower case. So Unicode rightfully introduced a separate codepoint specifically for that use case in 2008.
This inspired designers to design a glyph for that codepoint looking similar to ß. Nothing wrong with that.
Some liked the idea and it got some foothold, so in 2017, the Council for German Orthography allowed it as an acceptable variant.
Maybe it will win, maybe not, but for now in standard German the uppercase of ß is still SS and Unicode rightfully reflects that.