Hi Nicolas,
Did you mean the Viva daily briefing email?
Please first have a check via this link to see whether you have unsubscribed this service.
And since the content of the briefing email is based on the follow-up emails or up-coming meetings, would it be possible that you didn't receive follow-up emails?
If yes, it may be possible that Viva insights did not have enough contents to send a briefing email.
Reference: Briefing email from Microsoft Viva FAQ
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