The dash-dot broken lines show the display screen or portion thereof and form no part of the claimed design. The dash-dash broken lines in the figures denote portions of the display screen or portion thereof with a graphical user interface that form no part of the claimed design. The dash-dash broken rectangular line indicated by the number “2” in
The ornamental design for a display screen or portion thereof with a graphical user interface, as shown in the figures, may be within a graphical user interface of a computing system, such as a computing system utilized for robotic surgery.