EDIT: Does this mean he has used secrect messages in Facebook messenger?

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I’ve never used secret messages, so my device isn’t connected. Does this mean my husband is using secrecy messages on his phone?? When you click on his device, there is a “key”, a long list of numbers/letters. Help!

Edit: my husband and I have turned off secret messages on both our our phones, about a month ago because they were automatically turned on. He claims that he doesn’t know how secret messages got turned back on.