@TheSinnohStaraptor Basically they just put in a coat of arms with a religious symbol from the Germanic culture (The two-headed eagle from the HRE in this case) and called it Nationalist / Fascist by making it an ideological flag.
@Sovereign Crescent It is also a dynamic flag for the Fascism ideology however. The double-headed eagle is a symbol that should never be related with Fascism under any means. This also applies to literally any other symbol that was used during the HRE.