"Objednali jsme si bramborovou polévku." should not be marked as typo
"Objednali jsme si bramborovou polévku" is one of the accepted translations. Perhaps there was a typo in your answer. If you pasted your actual answer into your comment, there might be a Duo bug. (It wouldn't be the first time.)
I fear this was an audio exercise. Basically, we have to disable all audio exercises which contain ambiguous past participles with indistinguishable li/ly.