So the biggest changes are the switch to Java 16 and MC 1.17+!
Don't fret if you still use 1.16 though! While some features have been added, nothing is large.

The two new features are:

• 2 new ticket search constraints! closedby and lastclosedby
• The return of the plugin update checker! This feature briefly appeared in version 2.1.0 but was removed because of various reasons. With Paper/Spigot 1.17, this feature has been regained by the introduction of the server to install dependencies on server startup! This feature is here to stay!
  

A few other tweaks have been made, and a full list of changes can be found at https://github.com/HoshiKurama/TicketManager/releases/tag/4.1.0