The student is unable to see the "Accept Submission - Save" button and the bottom of the window appears to be cut off.
Example picture:
Have the student zoom their browser out until Turnitin renders properly.
Alternatively, the instructor can choose the load this tool in a new tab option in the Canvas settings for the assignment.
Turnitin appears to not reserve enough space for the submission window to render properly and is squeezed when there is a large amount of instruction above it.
Fix did not work contacting support.