From Flux Developer Wiki

Redo

The redo command undoes the previous undo command. The Redo command is only available after you use the undo command.

The Undo Redo system is Adaptive, that is it works much like a sophisticated word processor such as MS Word. When you Undo in MS Word, it undoes your typing letter by letter. As you continue to undo, it will start undoing word by word. Flux Studio works the same way. As you undo your actions, it will allow you to undo every detail of your actions. Flux Studio will later condense the continuous Undo Redo steps on a node to a single undo step.

There is also an Undo Redo History Window that shows all your actions since you opened the file.