Markup-Editor
In Confluence gibt es keinen Markup-Editor im eigentlichen Sinn:
You cannot edit content in wiki markup. Confluence does not store page content in wiki markup. Although you can enter wiki markup into the editor, Confluence will convert it to the rich text editor format immediately. You will not be able to edit the wiki markup after initial entry.
Confluence Wiki Markup | Confluence Data Center and Server 7.17 | Atlassian Documentation
Strg+Shift+V not working
as described here, there’s no chance to paste unformattet text in a table cell or a wiki page directly (source), although this key combination actually works in Edge and Chrome.