I have some .pdf files where the OCR recognition in graphics works perfectly, and the recognized text is also displayed correctly in the search results in the OCR tab, but I cannot find this text or its contents in the search index itself.

Does anyone have an idea why the OCR text does not appear in the search index?

The extracted text tab only contains very poorly recognized text, e.g.
"tems Ltg Am Rohiance 3 5S300 WetterCar"
"Invoice 12345 6 AV"

In the OCR tab the text is correctly recognized:
"Car Systems Ltd Am Rohlande 3 58300 Wetter"
"Invoice 123456 /W"

A search for "123456", for example, returns no results. I'm a bit at a loss right now.