Agree for future, but maybe not for Ubuntu 24.04. At one time I guessed version bump was GTK2 removal. I did find and install https://packages.ubuntu.com/noble/gtk-sharp3, but launch still failed:
$ mono ./Duplicati.GUI.TrayIcon.exe
Unexpected error: System.TypeLoadException: Could not load type of field 'Duplicati.GUI.TrayIcon.GtkRunner:m_trayIcon' (1) due to: Could not load file or assembly 'gtk-sharp, Version=2.12.0.0, Culture=neutral, PublicKeyToken=35e10195dab3c99f' or one of its dependencies.
at Duplicati.GUI.TrayIcon.Program.RunTrayIcon (System.String toolkit) [0x00027] in <3ea059db9f9241b999c39793a8f6f091>:0
at Duplicati.GUI.TrayIcon.Program.StartTray (System.String[] _args, System.Collections.Generic.Dictionary`2[TKey,TValue] options, System.String toolkit, Duplicati.GUI.TrayIcon.HostedInstanceKeeper hosted, System.String password, System.Boolean saltedpassword) [0x00066] in <3ea059db9f9241b999c39793a8f6f091>:0
I found the .csproj file, and found the BuildSupport folder, and guessed version gets built in.
Short of running Canary (which works well now except for some UI, but has other work coming), short of seeing if versioning can be tweaked for a 2.0.8.1 hotfix (for everyone or just this issue?):
Duplicati not been installed in Linux Mint 22 has a not-great workaround for these new OS: