why the text block in page is not all removed, (the text block in the chart and near the chart), how can I only remove all the text blocks and not impact drawings

[ytcpub]

test1.pdf

after run the following code, there are some text blocks removed successfull and some text blocks is not cleaned or removed

test_pdf = 'test1.pdf'
doc = pymupdf.open(test_pdf)
page = doc[0]
blocks = page.get_text("dict", sort=True)["blocks"]
txt_blocks = [blk for blk in blocks if blk['type'] == 0]
for blk in txt_blocks:
page.add_redact_annot(blk['bbox'], fill=False)
for line in block.get('lines', []):
for span in line['spans']:
page.add_redact_annot(span['bbox'], fill=False)
page.apply_redactions(images=0, graphics=1, text=0)
doc.subset_fonts(verbose=True)
doc.ez_save(test_pdf.replace('.pdf', '_remove.pdf'))
doc.close()