Site page text webpart Header 1 missing

It seems like you're encountering an issue with the available heading styles in the text web part in both Teams and Communications sites. This issue might be related to settings or updates that have been applied to your SharePoint environment or Office 365 tenant. Here are a few steps you can take to troubleshoot and potentially resolve the problem: Clear Browser Cache: Sometimes, browser caches can cause unexpected behavior. Try clearing your browser cache and refreshing the page to see if the missing "Header 1" option reappears. Check Tenant Settings: Make sure to check if there have been any recent changes or updates to your Office 365 tenant settings or SharePoint configuration that might have affected the available heading styles. Update or Reinstall Office 365 Apps: If you're using Office 365 desktop apps (Word, PowerPoint, etc.), ensure that they are up-to-date. Outdated apps might not display the latest options correctly. If the problem persists, you could consider uninstalling and reinstalling the apps. Browser Compatibility: Ensure that you're using a browser that's fully supported by your SharePoint version. Sometimes, certain features might not work correctly in outdated or unsupported browsers. Custom CSS or Styling: If you or your organization have applied custom CSS or styling to your SharePoint sites, it's possible that this customization is causing the "Header 1" option to be hidden. Check if any customizations are affecting the styles in the text web part. Tenant-Wide Settings: If you're an administrator, check if there are any tenant-wide settings or policies that might be impacting the available heading styles. Sometimes, permissions and settings can restrict certain formatting options. Contact Microsoft Support: If none of the above steps resolves the issue, it might be a bug or a more specific configuration problem. In such cases, it's a good idea to reach out to Microsoft Support for assistance. They can provide tailored solutions or insights based on the specific setup of your SharePoint environment. Remember to document any changes you make and their outcomes, as well as any error messages you encounter. This information will be valuable if you need to involve technical support or further troubleshoot the issue.