OpenNMS Horizon 23.0.1 is an update to Horizon 23.0.0. It contains a number of bug fixes and enhancements, including additional HTTP proxy support, reliability updates, UI performance improvements, and a number of Kafka-related fixes.
For a high-level overview of what's changed in OpenNMS 23, see What's New in OpenNMS 23.
The codename for 23.0.1 is Endora.