Text viewer broken for longer sentences

Steps to reproduce

1. Create a text file with a long sentence in one line. (Like in image 1)
2. Open it in the App
3. After a few lines, the rest of the sentence is jammed into one line.

Expected behaviour

Is is expected that the long sentence is split into several lines just like it is done for the first 6 lines.

Actual behaviour

After the 6th line, the splitting stops and the remainder of the sentence is just one line with horizontal scrolling.

Screenshots

This image shows the sentence in a normal text editor. Please note the line numbers on the left

This is the same sentence in the App.

If I scroll to the side, you can see that the enormous length of the last line of every sentence:

Reasoning or why should it be changed/implemented?

This has been correct in the past (1 or 2 years ago), but I cannot say when exactly this bug happend.

Start by reproducing the issue in the iOS App with a text file containing a long single-line sentence, then trace the text viewer entry point responsible for wrapping after the sixth line. Done means the remaining sentence continues wrapping within the viewer instead of requiring horizontal scrolling.