Grid forming (GFM) control significantly alters the fault characteristics of the power systems, posing challenges to conventional sequence-component-based protections, including directional and phase selection elements. This paper develops a unified sequence network model for GFM inverter-based resource (IBR)-dominated power systems, identifying the specific control loops that impact sequence-component-based protection. It is revealed that the current-limiting control loop significantly influences the X/R ratio of IBR equivalent sequence impedances, further adversely affecting protections relying on negative-sequence components. The theoretical analysis is validated through controller hardware-in-the-loop (CHIL) tests.