Vim stretches out highlighted sections, sometimes across multiple lines

posting on behalf of @oblitum

## Information

**VIM version** vim 8.1.542

Operating System:

## What went wrong

Either ALE or Vim extends highlights when the text inside of a highlight is modified.

https://i.imgur.com/NpEWq5C.gif

## Reproducing the bug

1. Edit a file with a highlight, with a linter that requires files to be saved
2. Press enter when in a highlight section

### :ALEInfo

Start by reproducing the issue in Vim 8.1.542 with ALE and a linter that requires files to be saved, following the reported steps. Compare whether ALE or Vim extends the highlighted section after pressing Enter; done means highlights no longer stretch across additional text or lines.

Written by the indexing model from the issue text.