Is it appropriate to fly a flag that has fewer than 50 stars?
Yes. Official United States flags are always considered living, active flags. From the Betsy Ross flag to the present 50-star flag, any flag that at some time was the official flag is still considered a living flag to be accorded all due respect.
https://www.ushistory.org/BETSY/faq.htm
Is it appropriate to fly a flag that has fewer than 50 stars?
Yes. Official United States flags are always considered living, active flags. From the Betsy Ross flag to the present 50-star flag, any flag that at some time was the official flag is still considered a living flag to be accorded all due respect.