"Quota was used" warning message
If you start seeing a warning message like this one on your WordPress dashboard...
...it is because you're using the Autoptimize plugin with the option to serve optimized images from the ShortPixel CDN.
You can choose to either add more credits to your ShortPixel account and keep using ShortPixel, or you can just deactivate Autoptimize's image optimization component as described here.