If you use "OK Google" to call the assistant on your phone, things will change. Google removes the "Unlock with voice matching" feature, so the assistant will be much safer.
If you use the "Unlock with Voice Call" feature, you can completely unlock your phone with Google Assistant just by saying "OK Google". While it's comfortable, this is also a pretty big security risk ̵1; your voice isn't exactly the best way to verify you're, you, you. If someone else's voice is just as big for your own, they can easily use this to unlock the phone and get full access to it.
But now Google removes that feature from all Android phones. It started with Pixel 3 and 3 XL, but confirmed that it would also get preserves on all other Android devices in the future – a future that has apparently emerged. Moto X and Pixel XL are the first devices to lose this functionality, so it shouldn't be too much longer before it is removed on others.
Of course with this increase in security you also get a loss in functionality. Anything that would require you to unlock your phone, e.g. Sending a text message is no longer an option. It's kind of a bummer, no doubt, but it's a trade-off that's worth it.
Without the Voice Unlock function, Assistant will be limited to "personal results" only. According to 9to5Google, this includes:
- Email, including personalized results from Gmail, such as flight bookings and invoices
- Google Calendar
- Memory Tools
- Shopping Lists
Everything More to require the phone to be unlocked before proceeding. Similarly, you can no longer press the home button to go home immediately after calling the assistant. You must unlock the phone with your PIN, pattern, password or biometric verification first.
9to5Google via Engadget