The HomePod does something similar. I had a friend bring over their HomePod and listened to a bunch of stuff in various rooms. It was an absolutely glorious background speaker. No real sweet spot and a consistent volume across all frequencies in any part of the room. It also had no dynamics and rolled-off highs of real instruments but also overly tight highs (giving an unreal clarity to the recording) of drum machines / electronic music. Something great for a background speaker as the music never distracted from the company that was over visiting. Would never use it for any serious listening.
I suspect, although I’ve never heard it, this Alexa speaker is doing the same thing. That’s the sound signature these speakers are aimed at and it’s what they do well with their DSPs and various speaker arrays. So, from a small speaker, I suspect the audio is pretty darn good but no one is overcoming physics with these designs. It’s still a small speaker producing small speaker dynamics and a weird, unnatural, clarity because of the heft of DSP processing happening. If you need background music though… they are a very good design.