If you are holding off upgrading to Ventura because of Mellel, don't. According to our tests and user reports. The current version of Mellel, 5.1.3 works well under macOS 13.0 and we have not received any reports of any issues specific to this version of the operating system. Feel free to upgrade to Ventura (looks like a good release too) and expect to continue working with Mellel as you always did.