Meta explained this feature earlier in August. Now some people can actually use it. WABetaInfo found Scam Alert running in WhatsApp for Android beta version 2.26.34.1, which usually means a public release isn’t far behind.

Only Android beta testers have it right now
The feature is live for a limited group of testers on version 2.26.34.1, and Meta hasn’t given a date for when everyone else gets it. No word on iPhone yet either. Development started back in June, so this has been in the works a while.
You have to switch it on yourself under Settings then Account
Scam Alert is optional and stays off until you enable it manually. That’s a small detail with big consequences, because plenty of people who would benefit most from a warning like this will never dig through a settings menu to find it.
It only checks messages from people who aren’t in your contacts
Once enabled, a small machine learning model gets downloaded to your phone. It reads incoming messages from unknown senders and compares them against patterns pulled from conversations that have already been reported as scams. Saved contacts are left alone.
The warning shows up in the chat and the sender never finds out
Only you see the alert, and there’s no notification on the other end telling them they’ve been flagged. From there you can either mark the sender as trusted or block and report them.
Nothing you receive leaves your phone unless you decide to send it
The whole check runs on the device. Meta’s blog post put it plainly: no message content leaves the device for classification, and nothing gets auto-reported to WhatsApp, Meta or anyone else. The one exception is voluntary. If you mark a chat as trusted, WhatsApp asks whether you want to share the last five messages to help the model get better at telling real conversations from fake ones.
That’s a reasonable trade, and it keeps end-to-end encryption intact, which is the part Meta was clearly most anxious to spell out.