I'm a professional editor for photographers. The photographers send me LR catalogs with smart previews attached for me to edit, and I return to them via the same catalog.
Since the new LRC 10.0 update, any grain in the edit is exploded by 10 times. So much so that it is hard to edit the images. I am also seeing this issue on my own native photos when they are "loading" but eventually return to normal. It seems to be a glitch with the smart previews and downsizing/sampling of the files. We've never had this issue before when catalog sharing with smart previews.
Will this glitch be fixed?
Examples: Both shot with GFX 50s 63mm lens, nearly identical ISO and SS. Both edited with identical grain and settings Girl Image | from my files, with RAW files available. This is fine, no issue Tablescape Image | from a Catalog with Smart Previews. Extremely grainy and can be worse at times to the point that the grain has to be turned off to edit and then reapplied.
For both your posting in this community page, and your posting at the feedback site. Please provide System Info as LeC reports it. Below is my SOP on this
Please post your System Information as Lightroom Classic (LrC) reports it. In LrC click on Help, then System Info, then Copy. Paste that information into a reply. Please present all information from first line down to and including Plug-in Info. Info after Plug-in info can be cut as that is just so much dead space to us non-Techs.