Are you talking about the adapters that let you run network through your electrical circuits? Because that’s different from PoE. PoE is running power through the network cables so you get power and network with one plug, so kind of the opposite of that.
I can confirm that using electrical infrastructure for network is really not great.
Some still are. Bigelow I think.
But loose leaf tea is much better quality anyway and avoids the issue of what’s in the bag entirely. They also have ceramic filters so you can completely avoid having plastic in contact with hot water