@supertommi If the images are coming out a lower resolution than you expect them to, check whether the width/height settings accurate to match the images, or alternatively disable cropping (under Advanced Settings).
If still low res, it’s very likely another plugin, typically something like a lazy load plugin, or something manipulating image output. JetPack’s CDN sometimes will conflict. if JetPack, this code snippet may still work to disable it for MetaSlider images: https://gist.github.com/KevinBatdorf/e6c6ab1dc57bff5ec411f8297fe92aa9
But the quickest way to figure out what plugin is conflicting is to disable them until the issue goes away.
If you have a URL of the slider on a test page, I can typically tell you in 5 seconds what the issue is, so feel free to tag me if you want me to take a look.