Redshift evolution of magnetic field strength in TNG-Cluster up to z = 4. We simultaneously show the magnetic field strength within 10 pkpc (circles), within 0.5r_500c (squares), and within r_200c (diamonds) as a function of halo mass M_500c. The black lines show the evolution of three individual representative halos for all three apertures. Along these trajectories, blue, purple, and orange markers indicate the CC state based on central entropy. We see that cluster magnetic fields amplify rapidly at all scales until z ∼ 2, after which the behavior becomes more complex and depends on distance and CC state.