M–R diagram for WDs in the ﹩f({ \mathcal R },{{ \mathcal L }}_{m})﹩ gravity model with a square-root exponential coupling. The dimensional parameter β has units of inverse pressure, [β] = cm² dyne⁻¹, and is fixed to the dimensionless value ﹩\tilde{\beta }=2﹩ throughout this work. The coupling parameter γ varies from −2.0ζ to 5.5ζ, with ζ = 10⁻¹. The solid black curve represents the GR prediction, while the dashed curves correspond to different values of γ