The word "banderole" was borrowed from French
The word "banderole" was borrowed from French. Banderole, "pennant, little ribbon", goes back to the Italian banderuola, "little flag".
Bandera comes from the Italian word bandiera, "banner, flag".
Banderuola and bandiera go back to the Proto-Indo-European root meaning "to bind", as in the Old Germanic bandwa, "sign" or "banner". Later this root branched out.
So it turns out that a banderole and a banderovets (a follower of Bandera) are distant relatives.