I have on my phone (Iphone 8s) the Lightroom v.6.1.0 application and on my computer Lightroom Classic CC 8.2.
I made a PRESET from my phone on a forest photo, I wanted to have the same PRESET on my computer, so I exported the photo in DNG from my phone, I sent it to my computer, I opened it with my Lightroom Classic CC 8.2 software and from there I copied the settings of my imported photo.
I pasted the settings on the same original photo but I was disappointed with the result so I compared the two photos (the one from my phone and the one from my computer) with the same settings and the results are different. I don't understand why with the same settings I can have two different results.
Lightroom mobile doesn't fully support every possible setting in presets, and when you apply a preset with incompatible parameters, LR Mobile will apply the ones it knows how to apply. I don't remember which ones are compatible with LR Mobile, but a little poking around should reveal it.
I would recommend combing through the settings to see what may be different between the two. There has to be some setting that is driving the change. It could be hidden (like perhaps a local adjustment, or a color setting on a hidden tab) that you're not noticing. Some other places to look for hidden differences include color profile, process version, curves settings, etc.
Applying a preset doesn't do anything magical, it just applies the exact numerical parameters that were saved from the file where the preset was created. And since not 100% of the desktop settings are compatible as presets for mobile, you'll have to search for them. Perhaps someone here has a canonical list of the unsupported settings?
In the Presets panel, Lightroom hides presets that reference camera profiles that are not fully compatible with the current photo you are editing. You can choose to show those partially compatible presets that are hidden by default.
To show partially compatible presets in the Presets panel, click the three-dot icon in the upper-right corner of the Presets panel and deselect Hide Partially Compatible Presets.
You can apply partially compatible presets to incompatible photos, but only settings that are compatible will apply.