A family of Microsoft presentation graphics products that offer tools for creating presentations and adding graphic effects like multimedia objects and special effects with text.
Hi @TF526
I have tested on my side and here is what I noticed:
First, Syne font is not in the official font list for Office apps. Therefore, it could be due to incompatibility between the font and Office App, specifically PowerPoint.
Second, I did see the same behavior as yours. However, only Syne Bold is affected, it keeps reverting to Extra Bold.
Installing each variant of the font individually did not work also, if Extra Bold is not necessary, you can consider remove that style only. After I removed it, my Bold font will stay the same as previous.
Additionally, I found this article which has some similarities: Font weight keeps changing in Powerpoint - Microsoft Q&A
This could indicate a compatible issue especially for variable-width font. You can provide your feedback via Help > Feedback or raise feedback via PowerPoint · Community.
When you done submitting, feel free to drop the link here so I and other people can vote for you.
I hope this information helps.
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.