PDF Box flatten PDF causes weird spacing

I'm having an issue with PDF box flattening a PDF generated by Adobe Acrobat DC.

The Adobe Acrobat text field I created is absolutely the default text field.

In my example below, I have a PatientName field with the text value "Douglas McDouggelman".

When I flatten the PDF, here's what it looks like:

Anyone know what's up with this bizarre spacing?

It appears that the space + next character are combined. This is what it looks like when you try to select that character.

Code:

try (PDDocument document = PDDocument.load(pdfFormInputStream)) {
  PDDocumentCatalog catalog = document.getDocumentCatalog();

  PDAcroForm acroForm = catalog.getAcroForm();

  acroForm.getField("PatientName").setValue("Douglas McDouggelman");
  ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
  if (flattenPdfs) {                    
      acroForm.flatten();
  }
  document.save(byteArrayOutputStream);
}

I realized this PDF was from some other group who made it and who knows what they did. So I found the source word document, repeated the creation of the form from Adobe DC, added the fields back to the document, then it was totally fine.

PDF box was not the problem... it was some unknown incorrect step that the person who originally prepared the pdf did.