The image in question was cropped quite significantly, but even with the cropping, the detail in the cropped image on my laptop screen was so much higher than the smart preview on my phone.
By @Andy Baines
That's because the Lightroom desktop app on your laptop will always download the original for editing, even if you have also downloaded Smart Previews. But LrM on your phone doesn't do that if you have "Only download smart previews" enabled.....so you are comparing a heavily cropped original with a heavily cropped smart preview, and you've now seen the potential consequences of that.
All I'm saying is that you have to be alive to the implications of using smart previews only on your phone....I said "generally these are OK", but that also means that there will be times when it's not OK, as you have discovered. For folks that have their originals in the cloud, we have an easy workaround (i.e. use the "get this original" command), but for those that sync their images from LrC to the cloud they don't have any such remedy, as all that is in the cloud will be smart previews, and for those heavily cropped images there's not really a solution.
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