If you've enabled plagiarism control in your feedback, the 'Similarity' field will be visible in the Workflow. This provides a percentage showing how similar the submission is to other sources.
Once in the Feedback Editor, you can access plagiarism control by clicking on the → 'Similarity report' tab on the right side of the screen.
This will change the view of the document to highlight sections which have similarity to other sources. As shown in the screenshot above, the highlighted texts are those that have high similarity.
To go more in-depth and check which sources these comments are similar to, simply click on the → 'Detailed report' button. This will take you to the specific report on the Urkund website.
For more information about how to use Urkund, please refer to Urkund's guides available on the website, as well as here.