Vision Framework - Text Recognition - Cannot recognize some umlaut diacritics

I am using Vision Framework to recognize text in my app. However, some umlaut diacritics are recognized incorrectly, for example: Grudziński (The incorrect result is: Grudzinski).

I already changed language to DE (because my app needs to support DE text) and tried to use VNRecognizeTextRequest#customWord with usesLanguageCorrection but the result still is incorrect.

Does Apple provide any APIs to solve this problem? This issue also happens when I open the Gallery on my phone, copy text from images, and paste it to another place.

Vision Framework - Text Recognition - Cannot recognize some umlaut diacritics
 
 
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