Here are my highlights pulled up in Vim:

As you can see, Bookfusion gives you a lot of extra information when you export highlights. First, let’s get rid of the lines that begin with ##
Enter command mode in Vim by pressing esc. Then type :g/^##/d and press enter.
Much better.

Now let’s get rid of the color references:`
:g/^Color/d

To get rid of the timestamps, we must find a different commonality between the lines. In this case, each line ends with “UTC”. Let’s match that:
:g/UTC$/d
Where $ matches the end of the line.

Now, I want to get rid of the > on each line:
%s/> //g

Almost there, you’ll notice there are 6 empty lines in between each highlight. Let’s shrink those down into one:
:%s/\(\n\)\{3,}/\r\r/g

The command above matches newline character n 3 or more times and replaces them with two newline characters /r/r.
As we scroll down, I see a few weird artifacts from the book conversion to markdown.

Now, I want to get rid of any carrot brackets in the file. Let’s use the substitute command again here:
%s/<//g

Depending on your book and formatting. You may have some other stuff to edit.