What power supply is recommended for the ROG Strix B450-F Gaming, and are there any critical power connection warnings?

For a fully configured system, ASUS recommends using a power supply unit (PSU) that complies with ATX 12V Specification 2.0 or later and provides a minimum of 350W. If you plan to use two or more high-end PCIe x16 cards, use a PSU with 1000W or above to ensure system stability. You must not forget to connect the 8-pin EATX12V power plug — if it is not connected, the system will not boot. (Page 1-19)