The issue arises from curl's use of the outdated IDNA 2003 standard to handle International Domain Names, which may lead users to unknowingly issue network transfer requests to the wrong host. This is particularly problematic with domains using special characters, such as the German ß character, which is translated differently in IDNA 2003 and the modern IDNA 2008 standard. For instance, the domain `straße.de` is translated to `strasse.de` using IDNA 2003, but to `xn--strae-oqa.de` using IDNA 2008, potentially resolving to different addresses.