Why is Ember-Cli 3.14 throwing an ESLint No-New-Mixin error

I have three custom mixins that no longer work in Ember-Cli 3.14 (I had to step back down to 3.13.2). All I get is an Ember error saying no-new-mixins for each of the mixins. While the WebUI compiles and is hosted, the WebUI that is accessible no longer works properly. The errors appear to be thrown by ESLint.

Has anyone else had this problem with Ember 3.14?

https://github.com/ember-cli/eslint-plugin-ember/blob/master/docs/rules/no-new-mixins.md

I am hesitant to capriciously ignore a rule just because it does not get along with a new version of Ember, but works in others. So, I am checking with SO first.