Heading is affecting further than what's being highlighted

This only happens with copied/pasted text.

When you copy and paste content from a .txt file (like the one attached) and attempt to apply headings to a paragraph, Confluence will apply headings to more lines that you have initially highlighted. This probably happens because the content pasted on the page is not formatted accordingly (i.e there isn't line breaks between paragraphs) and that confuses the editor.

Steps to reproduce:

1. Copy a text with paragraphs (.txt)
2. On Confluence go to a page or a new page > Edit > Paste the .txt
3. Select a word or a phrase > click on Paragraph > Select a 'Heading' (1, 2...)

The 'heading' will be applied to all paragraph.