When you install a fibre optic card in a PCIe slot, then press the Attention button on the DPCC, you might see the message:
pciehp 0000:20:02.0:pcie04: Button pressed on Slot(3) pciehp 0000:20:02.0:pcie04: PCI slot #3 - powering off due to button press.
You can ignore this message.