How many M.2 slots does the ASUS PRIME B550M-A have, and what PCIe generation do they support?

It has one M.2 slot (M.2_1) that supports PCIe 4.0 x4 mode for NVMe SSDs, and a second M.2 slot (M.2_2) that supports PCIe 3.0 x4 mode.

Report 012084. Filed.