CKEditor adds extra  tag
You need to modify these settings to CKeditor.

// The writing rules for the &lt;p&gt; tag.
writer.setRules( 'p', {
// Inserts a line break after the &lt;p&gt; opening tag.
        breakAfterOpen : true,
}


This can either be set programmatically, via JS or I believe you should be able to add it directly via the UI, if you visit the Ckeditor settings page, there should be a box where you can enter ckeditor settings.

For more info see ckeditor docs: https://docs-old.ckeditor.com/CKEditor_3.x/Developers_Guide/Output_Formatting