Scrolling can alter highlighting incorrectly

[jmfd]

Occurs on: macOS 13.5 Beta (22G5048d); I did not test to see if this is a macOS regression.

Please see the video:

Screen.Recording.2023-06-27.at.11.03.40.AM.mov

Notice that the text below the headers changes to bold or not depending on how it is scrolled. This is incorrect, the text should not become bold in this case.

Here's the text I'm using:

# header 1

## header 2

### header 3

#### header 4

##### header 5

###### header 6

This is **bold** text.

This is *italic* text.

This is _underlined_ text.

This is ~~strikethrough~~ text.

This is <!--commented out--> text.

This is `code`.

> this is block quoted text

    this is verbatim