In this game I was black and was reduced to moving the rook and king back and forth at some point, and the computer says a huge advantage for white. What is the plan for white and how can he crack open the position?
Around moves 25-30
I'd maybe post the light squared bishop on a4 to stifle any hint of Black's counterplay there (that bishop has little else to do anyway) and then invade with the rooks and queen on the kingside. Black is so tied up there should be little possibility of defence to that plan.
You also have the idea of advancing the kingside pawns with g4/h4/g5.
it's very simple , black pieces including queen are stuck while Yours are free to Act, so all You have to do is to make sneaky move pawn g4 for example on 23 move, and then You may crack f6 sqare with that pawn, while Your Queen is close to his King, it's very dangerous for him, since his own queen is stcuk and far away, also You have supportive strong Knight there
btw that move of mine g4 and then go for cracking even SF doesn't recommends as first , but after It Advance rises even up to 6+
