After the Octane upgrade, all observers were broken. Replacing them with render modifiers fixed the issues and also removed the last remaining deprecation warnings.
The ScrollingObserver component doesn't use any Ember observers anymore, but still contains the word "observer". So I had to add an ESLint config line to ignore the "ember/no-observers" rule to the component.js file.
raucao
commented
4 years ago 
Fixes #203
After the Octane upgrade, all observers were broken. Replacing them with render modifiers fixed the issues and also removed the last remaining deprecation warnings.
The ScrollingObserver component doesn't use any Ember observers anymore, but still contains the word "observer". So I had to add an ESLint config line to ignore the "ember/no-observers" rule to the component.js file.