As part of the "Pick a sentence" step (T251551) of the Section Translation mobile editor, users can select sentences that have been already translated. In such case, the card does not show the proposed translation (T259502), but information on the translation provided by the user and an option to edit it.
The affected text is shown highlighted in blue, and options to inspect the whole paragraph may be available.
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You can check for more details in the parent ticket: T251551: Section Translation Editor: Pick a sentence