My images have a poor quality on mobile devices every since the 2018 update what can I do to fix this?
A very short statement with a question included isn't much for us to go on.
Any chance you could be a bit more descriptive?
What kind of images (file type)?
Size in Muse?
What 'mobile device'?
What does 'poor quality' mean in your situation?
etc etc etc
Images are blurred on all mobile phone devices, desktop ok, images are png or jpg using responsive site with break points the problems seems to be only on mobile break points.