One of my pet peeves when it comes to alternate history socialist symbolism and terminology, is how often it completely erases the history and legacy of the country taken into consideration, in favour of direct or indirect emulation of the OTL Soviet Union; there's nothing inherently reactionary about the US flag, for example - in fact, it could be easily adapted to the new socialist framework, with the upper left canton displaying not just the states of the federation, but also the new African American/Native American autonomous entities.
I mean, if the US flag is a reactionary symbol, the name "America" itself might be even more reactionary: at least the former is a revolutionary symbol, rather than a term that a lot of Native American peoples might associate with genocide and oppression.
The abolition of nationalist symbolism is in fact, on purpose as a break from the liberal past. it's as old as the Paris Commune where they abolished the Tricolour because the Blue and White were affectations towards elements that the Communards regarded as having no place in a classless society. The Warsaw Pact used defaced liberal national flags because almost all of them were not intended to be proletarian dictatorships but rather progressive coalitions involving liberals ("people's democracy") and thus they didn't wish to completely break with the liberal nationalists.
The proper name of the UASR is the "North American Union of Socialist Council Republics", it was envisioned as, like the USSR, not a replacement of its predecessor but the nucleus for a new socialist government to unify its region (europe and asia or the USSR, North America for the UASR) only for other circumstances to limit their ambitions.
The UASR also deplores the usage of the term "state" for its constituencies as "state" in such a context is nonsense to marxists and also the state framework is an obstacle to its hoped for absorption of all of North America into itself. An ambition the NAUSCR never completely loses sight of, as seen with its absorption of Eastern Canada and Quebec and their Indigenous nations as new republics in the union without regard for the old provinces rather than forming an independent Canada.
Though with the absorption of the Canaries and Ryukyu as constituent Republics into the Union "North American" is probably not geographically accurate anymore.
Also all attempts to make the Stars and Stripes socialist are hideous and the stars and stripes themselves are vexilogically dubious. The existence of American Havana using the Stars and Stripes also makes using the same flag as it a dubious proposition for the same reason why Communist China regarded using any variation of the White Sun flag a non-starter with Taiwan's existence.
Finally, as mentioned before, the French revolutionary left
hated the French tricolour, regarding it as an outmoded symbol of yesteryear's revolution to be cast into the dirt. From the Communards to the Syndicalists to the French Communist party, all wanted some variation of a red banner and to break ties with the 1789 flag which they saw as fundamentally a flag of liberal compromise. The American flag is
vastly more reactionary and far less revolutionary in what it stands for than the French three colour banner and would not pass the muster for the communists here.
The Comintern of TTL is also
aggressively anti-nationalist. The Comintern is sovereign and supreme over any national communist party or government, to the point of having the power to censure even the UASR and USSR in the cold war. These are not the OTL Soviets who recommended working with progressive national liberationists, these are ardent internationalist ultras who think patriotism is intrinsically suspect, at best a tool to cynically use and then discard when convenient, at worst something to crush as Romanian National Communism was subject to after the National communists in Romania went a bridge too far and brought about an "anti-counter-revolutionary" action in the country by the VOSCOM.
