Hello.
I has removed the checking of "Configure File Search" -> "Also index file content".
Then, 'only basic indexing=true' is recorded into ~/.config/baloofilerc.

$ grep 'only basic indexing' ~/.config/baloofilerc
only basic indexing=true

And, I realized that some parts of the file contents that I edited are sometimes indexed even now.
As a result, the offender is kwrite.

$ vi newfile.txt # create some multi-line text
$ cat newfile.txt
This is a pen.
Hello ballo.
hahaha.
$ balooshow newfile.txt
50675314103158790 2054 11798766 /home/yt/Documents/newfile.txt
$ kwrite newfile.txt # add one empty line
$ balooshow newfile.txt
50675314103158790 2054 11798766 /home/yt/Documents/newfile.txt
Line Count: 3

Like this, the file contents is indexed only by kwrite.

Can I stop this kwrite's behavior?
Thanks.

I'm using KDE neon.

$ balooctl --version
baloo 5.50.0
$ kwrite --version
kwrite 18.08.2