I realize a similar question to this has been asked, but it's not the same. The answers in that question are for older versions of MacOS. I'm asking this question specifically for MacOS Catalina 10.15.
In MacOS Catalina 10.15 on Safari, How to disable Command-I from composing a new Mail message
keyboardmail.appsafarishortcut
Best Answer
macOS has a built in method for changing/adding keyboard shortcuts
Note now that the Command-I in that menu has been changed to whatever you set it to, allowing you to set Command-I to something else, or just leaving it that way so you won't accidentally use it.