The release notes mention “improved sync stability for very low SNR.” In plain English: the software now handles the long, deep fades typical of 160m NVIS and gray-line propagation. You’ll notice fewer partial decodes and more clean callouts, even when the band sounds dead to your ears.
The JTDX 2.2 branch introduced several distinct features that separate it from the upstream WSJT-X project: jtdx 2.2 160
If you’re new to JTDX on Top Band: