When Francis Scott Key wrote his poem (song) the flag had 15 stars and 15 stripes. The Union might go back to the standard of having one star and one stripe for each state.
Presenting the 23 stars and stripes:
IOTL they stopped using one stripe per state because it was becoming too much.
They might not want 13 stripes because 4 of those stripes would represent "traitor" states.
They might reduce the number of stripes to 9; the original number of colonies "loyal" to the United States.
Here is a nine strip, one star flag:
. . . and just for the fun of it, here is a nine stripe / 23 star flag, and a 23 stripe / 1 star flag.
. . . I think 9 stripes might work.