Display screen or portion thereof with a transitional graphical user interface

The present application is also related to U.S. patent application Ser. No. 16/860,818, filed Apr. 28, 2020, entitled “SYSTEMS AND METHODS FOR SHORT TERM PERSISTENCE BY UNLOCKING ADDITIONAL SYMBOL POSITIONS,” the disclosure of which is hereby incorporated by reference in its entirety.

FIG. 1 is a front view of a display screen or portion thereof with a transitional graphical user interface showing a first image in a sequence according to our new design;

FIG. 2 is a front view thereof showing a second image in the sequence; and,

FIG. 3 is a front view thereof showing a third image in the sequence.

The outermost broken line illustrates a display screen or portion thereof and forms no part of the claimed design. Stippling in the drawings is used to indicate a contrast in appearance, with no specific color or other feature being claimed. The remaining broken lines represent elements of the transitional graphical user interface that form no part of the claimed design.