Aeotec released a firmware update for this Z-Wave controller yesterday the 17th Nov 2021. The link is here: https://help.aeotec.com/support/solutions/articles/6000252294-z-stick-gen5-v1-02-firmware-update
Confusingly, the article is titled Z-Stick Gen5+ V1.02 firmware update but is is for the Gen5 device to bring it up to the same firmware as the Gen5+.
As I had a spare Z-Stick that I’m about to use for my clean migration to ZWaveJS I decided to risk it. The software runs on Windows only and there are two components - the device drivers and the firmware installer. It may be possible to use the ZwaveJS firmware installer as well, but I didn’t try this.
The update only took a few minutes and after unplugging and reinserting the device, the most noticable change was the colour cycling LEDs changed to solid Green to indicate the charge state of the internal battery. On the ZWaveJS console, the firmware changed from 1.1 to 1.2.
As with any firmware update, you do this at your own risk, so it would be wise to backup the device first using the Aeotec software.