How much power is the Pi port capable of delivering, or are you sending additional power to the PCIe adapter from somewhere else?
What SmartNIC are you using? Most SmartNICs that I'm aware of suck a decent amount of power, many more require significant external airflow. Are you using the Mikrotik active cooled one? https://mikrotik.com/product/ccr2004_1g_2xs_pcie
What SmartNIC are you using? Most SmartNICs that I'm aware of suck a decent amount of power, many more require significant external airflow. Are you using the Mikrotik active cooled one? https://mikrotik.com/product/ccr2004_1g_2xs_pcie