Sample of Sgr A^* EVPA measurements across the four ALMA spectral bands (B1–B4) from the four observing days of the 2018 EHT campaign. The EVPA values for each time sample have been mean-subtracted to emphasize the relative variation across frequency. The dashed lines represent the best-fit linear models of the form ϕ(λ) = ϕ₀ − RM(λ² − λ₀²), used to estimate the RM evolution curves.