Hello, Mickael Adhoc
Welcome to Microsoft Community.
Thank you very much for your valuable feedback. We know that you are not able to embed Excel into PowerPoint after updating Office 2019 to version 16.0.17328.20452. We fully understand the inconvenience this problem has caused .
We are delighted to hear that you have resolved the issue by reverting to a previous version (16.0.16731.20738). We will share your solution with other users who encounter similar problems in Office 2019.
At the same time, we have already submitted this issue in this UserVoice, you can also vote it. Your voice is important to us.
You can also send feedback through PowerPoint app. (Open PowerPoint > Feedback > I don't like something.)
If you encounter any issues in the future, please feel free to post again.
Thank you again for your understanding and support.
Best wishes,
Lucia Wu - MSFT | Microsoft Community Support Specialist