block lines does not match visually

[ytcpub]

test1.pdf
in this pdf,

import fitz
doc = fitz.open('test1.pdf')
page = doc[0]
page.get_text('dict', flags=0)

I found all blocks is line by line, for this two lines:
inoculant shelf life and activity was investigated by monitoring cell
viability and TCC degradation activity up to 20 weeks of storage

why these two lines belong to two diffrent blocks? espectially "cell viability and T " "viability " seems belong to next block line but it belong to pre block

how to make the right block\line ， is there any params to change it behavior？