"@Microsoft, are you going to fix this problem?"
You're not writing to Microsoft here. This forum is primarily user-to-user, although sometimes Microsoft support people and others also join in.
Microsoft is aware of font problems in 16.9. You should submit your own reports to Microsoft using Help > Send feedback in Outlook (this question is about Outlook, so I am assuming that is the app you are having trouble
with). In other apps, click the Smile button to send reports about font issues to Microsoft. Submitting reports within the apps is the way to let Microsoft know they have a problem to fix. The more reports, the sooner they will get to work on fixing this.
For questions concerning insider builds, please post those to the Insider forum.