I've got this line of text I'm trying to append to a text file using the below code.

HTML Code:
$TextToAdd = "<li>SDG gave a Lighten alert.</li><li>CPB gave a Pyramid alert.</li><li>OKN gave a Pyramid alert.</li><li>SHR gave a Lighten
 alert.</li><li>TRU gave a Pyramid alert.</li><li>BEN gave a Buy alert.</li><li>NAB gave a Sell alert.</li>";
PHP Code:
$linebreak = "\r\n";

//name of file to add info
$filename = "test file.txt";

 //Open file for append
$open_file = fopen($filename, 'a');
                
 //add to file
fwrite($open_file, $TextToAdd);

//add line break
fwrite($open_file, $linebreak);     
                
//Close file
fclose($open_file); 
However, when I open the file the text has been split up over several lines and looks like this??
HTML Code:
<li>SDG gave a Lighten
 alert.</li><li>CPB gave a Pyramid
 alert.</li><li>OKN gave a Pyramid
 alert.</li><li>SHR gave a Lighten
 alert.</li><li>TRU gave a Pyramid
 alert.</li><li>BEN gave a Buy
 alert.</li><li>NAB gave a Sell
 alert.</li>
Why is this happening and how can I ensure the text is displayed on 1 line of the text file?