The ornamental design for a displayscreen or portion thereof with an animatedgraphicaluserinterface, as shown and described.
FIG. 1 illustrates a front view of a display screen or portion thereof with an animated graphical user interface showing a first image of the sequence;
FIG. 2 illustrates a front view thereof showing a second image of the sequence;
FIG. 3 illustrates a front view thereof showing a third image of the sequence; and,
FIG. 4 illustrates a front view thereof showing a fourth image of the sequence.
The broken line showing of the display screen or portion thereof and the remainder of the animated graphical user interface forms no part of the claimed design. The appearance of the transitional image sequentially transitions between images shown in FIGS. 1 through 4. The process or period in which one image transitions to another image forms no part of the claimed design.