What is hogging my Ethernet in Windows?

To me it looks like the ethernet is not really an issue. The graph and value show 568kilobits which isn't particularly large. Brief spikes in traffic are not really an issue and the fact that the graph has not readjusted suggests that the spike is not much larger than what is seen.

My main concern is this:

You have at least 1 CPU core pegged and giving a solid 25% CPU use and 0.78GHz is a common speed for CPUs to be stuck at during a thermal or power throttling event that has locked the system down.

Often this is cleared either by rebooting, fully removing power for a period or otherwise clearing the CPU temperature issue.

If nothing else there is ThrottleStop which can be used to bypass CPU throttling. I've seen a few indications that disabling BD PROCHOT should release your CPU throttle in a lot of cases but bear in mind that if your CPU (or chipset or GPU which all may contribute) is overheating then this could actually be a bad thing to do.

In the first instance I would be looking at the easy fixes of rebooting the system including chipset and thermal sensors by fully removing power.

Repeated ethernet activity is nothing to be concerned about. Nowadays there are all sorts of processes that are constantly accessing the internet (via your ethernet) for completely legitimate reasons. Windows Update is a prime example, as (sadly) are many drivers nowadays (or to be more precise, the bloatware that's bundled with the driver).

Basically, if it ain't broke, it doesn't need fixing (apart from the likely CPU throttling issue that the other answer has noted).