Different preview in 100% zoom, Develop and Library modules

I was using Negative Lab Pro plugin in Lightroom Classic to convert my film negatives. The plugin generally works nice, but there's a problem of previewing these photos in Lightroom Mobile. They gets dark, contrasty and very ugly. Many people tried to solve this, but it seems that the probem lays on the Adobe side and it's been years since it was addressed but not fixed.

Finally, after years of waiting, I decided to switch from NLP to manually converting my negatives. I spent two whole days converting thousands of negatives and after 20+ hours I noticed that when 100% zoomed, it also gets dark and contrasty. I was working all the time with Smart Previews, the images looked nice, but then when I zoom 100% it gets weird, this time not only on mobile, but everywhere, including Lightroom Classic.

So, now I have thousands correctly converted Smart Previews, but when I export them, they doesn't look correct. If I zoom in at 100% and work on 1:1 preview, the Smart Preview that will be generated automatically will not look correct, so this time, I'll have weird photos in grid view and mobile. Exports will be fine though, but this is not the solution, because this is the main reason I switched from Negative Lab Pro.

I tried to search for the answer, but 90% of the time, people are referring to non-calibrated monitor, which I don't think it's case because I'm looking this on both computer with calibrated monitor and mobile versions on iPad and iPhone. They all looks the same bad. One more thing why I think it's not the monitor is because the correct preview appears for a few seconds until new one is generated.

Here's one example.

This is correctly converted/edited photo. I was unaware that I was editing smart preview.

This is how it changes when I zoom in at 100%:

This is a new generated preview when I get back to grid view:

Few more examples that went ugly after zooming in at 100%. These are at least 2-3 stops underexposed and with added contrast.

So, again, I can load 1:1 preview of each photo and then do the conversion, but in that case, the smaller generated previews gets opposite: bright and flat.

I also noticed that my medium format negatives, which are less grainy has less change in previews than my 35mm. It probably has to do something with that, but again, correct previews are shown sometimes in the grid view and then gets wrong after some time.