1. Edit a topic with two paragraphs or more.
2. There is a whitespace before the second (and later) paragraphs' beginning even when the user didn't add it.
See https://www.mediawiki.org/wiki/Topic:Se6p2ic73417viw1 for example. I didn't add a space before the "More again." but it's there when you try to edit.
Merging in T94372 -- probably the same issue:
As in the case of TABs (T93851), these `<nowiki>` tags are not wanted, and Flow should not be adding them:
* https://pt.wikipedia.org/w/index.php?title=T%C3%B3pico:Segoxqgdyct4l8f6&action=compare-post-revisions&topic_newRevision=segpnrtx6c48dipl
* https://pt.wikipedia.org/w/index.php?title=T%C3%B3pico:Segov5w2cbzfrzck&action=compare-post-revisions&topic_newRevision=seq3ivfqufaatqo2
* https://pt.wikipedia.org/w/index.php?title=T%C3%B3pico:Segsdt3rteotwijl&action=compare-post-revisions&topic_newRevision=seh4f4stv64b7hl3
The first two was breaking the list syntax, and the last one the link syntax.
The formatting of
```
<pre>{| class="wikitable"
|-
! A !! B
|-
| C || D
|-
| E || F
|}</pre>
```
was also broken while previewing it for creating this topic: https://pt.wikipedia.org/wiki/T%C3%B3pico:Sevu5yugkcry06tu. After it was saved, and the page is reloaded, it looks ok, but it is broken due to unwanted tabs if I preview, or edit the source code.