Are you also "never using them" like OP and they send/receive that much data? Curious what it is since the Sidewalk thing seems to be limited to 500MB across your account.

I use them multiple times daily, but essentially only for things like "turn off the lights", "set a timer for 30 minutes", or "add cheese to my shopping list". But “Echo A” is probably my most-used device, so usage doesn't seem to be very correlated with the bandwidth consumed.