For those who trust me:
Goto your Amazon account, sign out of all your devices, everything, everywhere all your Echos (yes I know it's a pain), reset your password, delete 2FA and any tokens and reset them. Now.
That doesn't include Fido / Yubikeys but does include Auth tokens.
Do it now.
As much a pain as it is to reset Echo and all smart devices, trust me, please do it.
I can't tell you more yet, but I am being ethical and you need to actually realise I have a clue.
It's been a scary day