The datasheet on page 133 shows different signalling speed 1.25GBaud/3.125GBaud for the input/output timing at 2.5GbE/SerDes.
What are the correct values?
BCM53134O SGMII interface supports 1Gbps and 2.5Gbps speed.
Right, it is typo in datasheet [2.5GbE/SerDes Timing] section. For input timing, the receive Data Signaling Speed is 3.125 Gbaud and not the 1.25 Gbaud.
The datasheet will to update to correct the typo in next update release.