Why does the font under the barcode become thicker after saving the pdf file

[XMQSVIP]

Why does the font under the barcode become thicker after saving the pdf file? Other fonts are normal
1.pdf

pdf = fitz.open(path, garbage=4, deflate=True, clean=True, pretty=True)
pdf.save(path

[JorjMcKie]

Please provide reproducing data. The link above does not work.
As an immediate remedy: do not use clean=True ... even if it sounds so reassuring 😎.

[XMQSVIP]

Thank you. Your solution was the right one