A Hotfix has been released for SKYPE for Business server 2019 – although the Download site says Cumulative, it is in fact only a HotFix.
The version for this patch is
To find your current patch level run this command on a SFB server
The HotFix is targeted at 2 very specific issues/ feature, if your environment suffers from neither it is 100% safe to ignore this patch.
Here is a KB describing the Trial Version issue
The other thing included is that the patch Enables Location-Based Routing to support Skype for Business mobile clients on SFB server 2019.