Welcome to the community. I've never known Red-eyed tetras to be aggressive, but I suppose it's possible. Does your tank have enough decor to provide line-of-sight breaks so the bullied fish can get away from each other? Also, tetras (and danios) prefer to be in larger groups than you have. Sometimes fish that are in a too small group are stressed and that can lead to aggression. IMO
, rehome the 2 danios and add 2-3 more red-eyed teras.