Why VFs are showing different speed then that of its physical interfaces or PFs ?

Issue

• An physical interface is showing speed as below;

~ ] $ cat sos_commands/networking/ethtool_enp5s0f0 
Settings for enp5s0f0:
    Speed: 10000Mb/s

• VFs configured form above physical interface or PF are showing different speed as below;

~ ] $ cat sos_commands/networking/ethtool_enp5s8f0
Settings for enp5s8f0:
    Speed: 9900Mb/s

~ ] $ cat sos_commands/networking/ethtool_enp5s4f0
Settings for enp5s4f0:
    Speed: 5000Mb/s

• What is causing this difference in speed ?
• Bond is configured using these VFs and all of them is showing different speed

~ ] $ egrep -i "slave|speed" proc/net/bonding/bond0 
Slave Interface: enp4s4f0
Speed: 5000 Mbps
Slave queue ID: 0
Slave Interface: enp4s8f0
Speed: 9900 Mbps
Slave queue ID: 0
Slave Interface: enp5s4f0
Speed: 5000 Mbps
Slave queue ID: 0
Slave Interface: enp5s8f0
Speed: 9900 Mbps
Slave queue ID: 0
~ ] $