There are garbled characters and some text, which can be copied inside a viewer, can not be found in the exctract_text()

Environment

$ python -m platform
Windows-10-10.0.22000-SP0

$ python -c "import PyPDF2;print(PyPDF2.__version__)"
2.6.0 

Code + PDF

This is a minimal, complete example that shows the issue (with #1136 to fix keyerror "\W"):

import os
import PyPDF2
pdf_filename="ST辅仁：2019年年度报告.PDF"
txt_filename="ST辅仁：2019年年度报告.txt"
with open(pdf_filename, 'rb') as pdfFileObj:
        pdfReader = PyPDF2.PdfReader(pdfFileObj)
        x=pdfReader.numPages
        with open(txt_filename,"a",encoding='utf-16') as file1:
                for i in range(x):
                    pageobj=pdfReader.pages[i]
                    text=pageobj.extract_text()
                    file1.writelines(text)

ST辅仁：2019年年度报告.PDF

Original PDF snippets

page 7/254:

copied from pdf file: 第二季度

TXT file finder

Example of garbled characters

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-Añ-��J �7 �]
-Añ�h1Ñ*6��
ˆ�J
�:�Ô�p �7 �:#§Añ�h�Ô�C�p
�\ œ
(�à œ
( �7 Eµ�ñ9Ÿ�JLö
��f9Ÿ6Ñ�-�9L€ œ
(

Eµ�ñ�2 �7 "ã ‡Eµ�ñ�2�f9Ÿ�9L€ œ
(
Eµ�ñLö
� �7 Eµ�ñ9Ÿ�JLö
��9L€ œ
(
�09ŸLö
� �7 �0�1�f9Ÿ�ÄLö
��Å�9L€ œ
(
�»"ãG‚�J �7 "ã ‡-1�»"ãG‚�J6Ñ�-�9L€ œ

here is the txt extracted:
ST辅仁：2019年年度报告.txt