Malformed XML debug data is not available on PHP 7.0+

[nitriques]

In PHP 5.6.x I get

<errors valid="false">
            <error>Data returned is invalid.</error>
            <item>loadXML(): Opening and ending tag mismatch: link line 8 and head in Entity, line: 11</item>
            <item>loadXML(): Opening and ending tag mismatch: meta line 6 and html in Entity, line: 22</item>
            <item>loadXML(): Opening and ending tag mismatch: head line 5 and rootelement in Entity, line: 22</item>
            <item>loadXML(): Premature end of data in tag html line 4 in Entity, line: 22</item>
            <item>loadXML(): Premature end of data in tag rootelement line 1 in Entity, line: 22</item>
</errors>

In PHP 7.0+, I get

<error>Status code 400 was returned. Content-type: text/html; charset=iso-8859-1</error>

It really bugs me out that I get a 400, because I know that the endpoint returns a 200.

I need to investigate.