For my blog posts i use <!--nextpage--> to short long articles. A few version ago this plugin work good with canonical tag for post pagination. For example i have: site.com/blogpost and and second page of this post site.com/blogpost/2, for both these links i have the same canonical "site.com/blogpost/", and the second link not indexed by google, and this is correct because i do not have duplicate titles and content (comments).
Now with new version is bad canonical work for pagination posts:
For paginated post there is also a canonical tag that points to the paginated post. For example, page 2 of pagination has a canonical pointing to itself. This is not good because in this case we have duplicate page with content (title+commnets).
Please add the old functionality of canonical links.