Found the debugging page.
Here's the info from the console:
DevTools failed to parse SourceMap: file:///Applications/Joplin.app/Contents/Resources/app.asar/gui/ResourceScreen.js.map
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/Applications/Joplin.app/Contents/Resources/app.asar/node_modules/react-dom/cjs/react-dom.development.js:11494 Warning: componentWillReceiveProps has been renamed, and is not recommended for use. See https://fb.me/react-async-component-lifecycle-hooks for details.
* Move data fetching code or side effects to componentDidUpdate.
* If you're updating state whenever props change, refactor your code to use memoization techniques or move it to static getDerivedStateFromProps. Learn more at: https://fb.me/react-derived-state
* Rename componentWillReceiveProps to UNSAFE_componentWillReceiveProps to suppress this warning in non-strict mode. In React 17.x, only the UNSAFE_ name will work. To rename all deprecated lifecycles to their new names, you can run `npx react-codemod rename-unsafe-lifecycles` in your project source folder.
Please update the following components: Connect(NoteTextViewerComponent), Connect(NoteToolbar), Connect(Toolbar), Connect(ToolbarBaseComponent)
In the log file, I don't know if this is normal behaviour but this stuff appears in the debugging mode every 4 seconds or so while I'm editing. (Could it be that it's saving/synching too often?):
2020-10-19 09:22:47: "Scheduling sync operation...", "30000"
2020-10-19 09:22:50: "Saving note...", "{"id":"0e6e82daa78241c7bfe71016aa5911ea", <contents of note here>