**Steps to replicate the issue** (include links if applicable):
* Go to https://en.wikipedia.org/wiki/Wikipedia_talk:WikiProject_Catalan-speaking_countries
* Be in Vector 2022.
* Use the default MediaWiki editor from 2003
* Disable Visual Editor
* Click the [edit] link at the top right of the page, to the right of the page title, to edit the lead section
* Do not make any changes in the edit window
* Click "Show changes"
**What happens?**:
* You will see a diff showing that a blank line has been inserted after the contents of the lead section and the first second-level header, even though you have not added that line in editing
**What should have happened instead?**:
* No blank line should be inserted, since the editor has not added a blank line. The MediaWiki editing software should not insert characters that the editor does not insert themselves.
**Software version** (on `Special:Version` page; skip for WMF-hosted wikis like Wikipedia):
**Other information** (browser name/version, screenshots, etc.):
I have been clicking [edit] and then Publish on the lead section for over ten years in order to do a quick null edit on pages. Just in the last week, I have occasionally been prompted for an edit summary (by the "Prompt me when entering a blank edit summary" preference), because the software thinks that I have added a new line. The new line appears to be added by the MediaWiki software (or a gadget, maybe). I have not changed any preferences or relevant .js, to my knowledge.
This issue does not always happen. I believe that this issue happens only when there is no blank line between the lead section content and the first level-two header. For example, this issue does not happen at https://en.wikipedia.org/wiki/Wikipedia:WikiProject_Catalan-speaking_countries/Style_advice where I can click [edit] and Publish without triggering the addition of a new line.
Possibly related: T2156