Hey ZenMoto, i tried it and unfortunatly it doesn’t fix the problem. But it could be related to Obsidian rather than to the Mac settings because it does not happen when I type — in TextEdit…
I got it!
Looking at the Obsidian settings and extensions was the key! The plugin Smart Typography has one option called Dashes:
Dashes
Two dashes (–) will be converted to an en-dash (–). And en-dash followed by a dash will be converted to and em-dash (—). An em-dash followed by a dash will be converted into three dashes (—)