Brute forcing the new Facebook Messenger end-to-end encryption seems easy

I got an alert when I opened messenger this morning (which I'm forced to use due to family members), saying they are now using end-to-end encryption in messages and for me to setup a 6 digit pin.

I have no option of setting a longer pin, or using anything other than digits. This doesn't sound very secure to me. Surely if the only thing keeping my messages encrypted is this 6 digit pin, it's easy to brute force.

If Facebook …

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