Observation Details
Link "Datenschutzhinweise" will download a PDF document. PDF documents must be made accessible as well. As PDF documents are out of scope for this audit, the document's accessibility is not evaluated.
As the user experience for all users is the same with this observation, it is not considered a failure under success criterion 2.4.4 Link Purpose (In Context).
Remediation Notes
It is best practice to inform users of the purpose of a link before the link is clicked. In this case, informing about the download of a PDF document would be best practice.
Ideally, the document is opened in the browser instead of being downloaded right away, so the user can decide if downloading the document is necessary and wanted.
Either way, a hint about the click linking to a PDF document instead of a website may be given to the user, e.g. as "Datenschutzhinweise (PDF)".
Side note: the nesting of interactive elements is noted in another observation as well. The link inside the input label will reduce the target area of the input and may lead to mis-clicking. Ideally, the Instructions, including the link to the document / website, is preceding the actual input element. The structure could be based on:
<p id="hint-datenschutzhinweise">... <a href="...">Datenschutzhinweise (PDF)</a> ...</p>
<input type="checkbox" id="input-datenschutzhinweise" aria-describedby="hint-datenschutzhinweise">
<label for="input-datenschutzhinweise">Ich habe die Datenschutzhinweise ...</label>