In the old versions of Alexa and Google Assistant (before LLMs), you could memorize a couple of voice commands that they'd reliably recognize to do a really basic task. If you need an oven timer but you've got meat juice on your hands, you yell, "Alexa, set a 30-minute timer!" If you want to turn your bedroom lights on without fumbling in the dark, you yell, "Hey Google, turn on my lights!". That was, like, the main thing they were sold for.
But then Google changed the default voice assistant on Android to use Gemini. So instead of relying on hard-coded "if the user says this exact phrase, do the thing we said would happen" conditions, people now have to hope the model's smart enough to figure what "turn on my lights" means from first principles every single time.
Alexa users are much more terse and impolite, I just yell “Alexa, {time period}!” :) this still works - as does personal phrases for doing an action.
Alexa is also still very specific though. You can say “turn on bedroom” if the lights are named such, but “turn on the bedroom [lights]” will fail. I’ve always found that frustrating, but it does have the advantage that it’s very reliable if you use the right phrasing.