How exposed is my data/home network using smart plugs from amazon?

I've had a few for a couple years now on various devices. I like them a lot and use 2 on heavier usage plugs to monitor how much energy both are passing through it so I can manage my electricity usage.

My account for some reason now doesn't exist with them even though I can give them all voice commands through amazon alexa. But when I go to the Smart Life app it says my account never existed and it won't allow me to recover it. This being some knock off chinese company there isn't really any customer service I care to deal with. So now I have to re add all the plugs and re intergrate them into my alexa routines. Pretty annoying.

But this made me question if these things have been on my network and I had to put my password into the app has this left me open to data siphoning or unknown infiltration of my network? All of these were purchased on Amazon but Amazons available brands seem to get more chinese and generic everytime I shope there now which is becoming less and less frequent.