Double AsciiMath

I have a strange submission on https://grady.informatik.uni-goettingen.de/cs2-2/sose21. Line 2 looks like this:

However, when I reset AsciiMath, I get this:

The additional line breaks probably come from the double dollars. But where does the additional "|xy|<=p" come from?

I can't give you the name of the participant, since the corrections are anonymous. The feedback was created on 22.08.2021, 12:54:42 and modified/validated on 29.08.2021, 18:49:59. Maybe this helps you finding it. (And maybe it convinces you that it might be a good idea to make the pseudonyms visible to tutors; but that's another discussion.)