jQuery `DOMSubtreeModified` gets a Violation message in Google Chrome

[summercms]

Using jQuery version: v3.4.0 and jQuery Migrate: 3.0.1 - yes I know old versions.

When I add the following code example:

$('#element').on('DOMSubtreeModified', function() {
        // do something
});

I get the following Violation message in Google Chrome 87:

[Violation] Added synchronous DOM mutation listener to a 'DOMSubtreeModified' event. Consider using MutationObserver to make the page more responsive.

Is this a bug in the latest jquery v3.5.1

[dmethvin]

The warning is because your code used a deprecated event. jQuery doesn't stop you from doing that. Consider using MutationObserver instead.