Nonprofit Starter Pack version 3.46 was pushed to sandboxes last night. The full release notes are available on Github:

The most notable new feature in this release is a feature to send Acknowledgment Emails to donors thanking them for their donation. Full details on configuring the feature, and using the feature, will be documented on the Power of Us Hub.

3.46 will be pushed to all production orgs on the evening of Tuesday, July 14. Please check your sandboxes and repot any issues before then.