Here is the solution for everyone, with different designs including the old Roon icon from 1.7 and the new icon for 1.8 (.ico is for Windows / .icns is for macOS). Please let me know if you are unable to download, the link is broken, or if you would like to give me some ideas to make more customized icons:
New Icon (Roon 1.8):
Some examples of what I did (Roon 1.8 Icon in Dark Mode | Roon 1.8 Square Icon):
What it should look like:
Notice: When replacing the old icons with the modified icons, make sure to restart your computer and/or reboot Roon if you do not notice the icon changes immediately. Also, after any future updates (including Build 756), be sure to save a copy of the icon since Roon will override with the new one.