Actually this flag was designed in the 1800s…It just never became official until later. It is almost identical to the Cuban flag designed mid-1800s, but the blue and red colors are reversed.
via Wikipedia: “In April 1869, Narciso López’s flag was designated the national banner by the Congress of the Republic of Cuba in Arms. López’s flag was the model for the flag of Puerto Rico adopted in 1892 by the Puerto Rican Revolutionary Committee, a pro-independence group that worked under the auspices of Cuban Revolutionary Party”
This has been Sheldon Cooper with today’s Flag Facts!