iMac network speed toggling when in standby

Hello,

I am using an M1 iMac that is connected to a TP Link switch (wired). Whenever the iMac is in standby the network port on the switch starts toggling between 100mbps and 1gbps. Whenever the iMac is in use it is working fine with 1gbps. Is there any reason the network speed changes while in standby? I am receiving mails from my monitoring software that the switch port seems to be faulty, because it falls back to lower speeds.

Thank you!