This type of issue with the Intel e1000e driver seems to have been an issue since at least 2013.
From my internet searching I have found people complaining about this happening from 2013 all the way up to 2024 and yours now makes 2025.
It looks like Intel has no plans to fix it and from the searching the solution that kept being used and said to fix the problem is to turn off gso, gro & tso in the nic. These are various off loading functions and I would expect that removing these would affect the performance to some extent.
If you want to do that you would need to run the command
ethtool -K red0 gso off gro off tso off
Which is what the users in the various web sites I found did.
https://forum.proxmox.com/threads/intel-nic-e1000e-hardware-unit-hang.106001/
https://serverfault.com/questions/616485/e1000e-reset-adapter-unexpectedly-detected-hardware-unit-hang
https://www.reddit.com/r/Proxmox/comments/1drs89s/intel_nic_e1000e_hardware_unit_hang/
https://gist.github.com/brunneis/0c27411a8028610117fefbe5fb669d10
However I suspect that when you reboot they would get turned on again so you would need to add that command into the rc.local file to get run during the boot cycle.
https://www.ipfire.org/docs/pkgs/rc-local
As to why it only started now, there was a kernel update in CU190 so either there was a change to the e1000e driver or something else changed in the kernel that causes the e1000e driver to hang.
The other thing that worked for some users suffering from this problem was a change of NIC but that is only feasible if the NIC is an add-in card.