Can anyone please explain why does the posts table inserts inline styles straight into the table? It makes it very difficult to use the rest api to fetch posts, as well as display them on my external site. I have to go through and manually filter out the inline styles with regex.

When you format content in a WYSIWYG editor, it typically applies inline styles. This is normal and expected.

If you want raw text content without styles, you'll need to use something like strip_tags() in PHP after fetching the post.