To distinguish between <pre>Foo</pre> and <pre>\nFoo</pre>, Parsoid gives us HTML like <pre><span typeof="mw:Placeholder">\n</span>Foo</pre> for the latter. We don't currently have any special handling for this placeholder in VE, so it shows up as an inline alien.
I'm asking the Parsoid team to remove it.
Version: unspecified
Severity: normal