Dog reactivity triggered by dog reactivity ???

I have a 9 month old street rescue (large breed mutt) who has reactivity issues. She’s a really sweet dog but I’m kinda at a loss on how to handle her behavior challenges. She LOVES dogs and people, however, if we are out on a walk and another dog shows any sort of aggression towards her it’s game over. She’ll start lunging, barking, and growling to the point that I almost can’t hold her back. I have to be 100% engaged in these moments or else I think she could slip my grip and something bad could happen. She does really well with her dog friends and at doggy daycare so I know she’s capable of being chill and good around dogs. How can I control her reactivity when it’s only triggered by other reactive dogs? It’s mostly just an issue out on walks (we don’t have a yard unfortunately), but she recently got into it with my brothers dog after my brothers dog bit her first. It’s like she has to come back at any aggression 10X harder. Has anyone else experienced this?!?