Update 1.6.640 is a necessary evil. It fixes no major long-standing bugs (the unofficial patch still does that) and introduces no new quests or features. However, it modernizes the game’s backend for Steam Deck and future Bethesda integration. For the average player, it’s a smooth transition. For hardcore modders, it was a weekend of updating DLLs.
For a full list of changes and fixes in Skyrim update 1.6.640, check out the official patch notes on Bethesda's website: skyrim update 16640 new
As of 7 days after the , here is the compatibility status of major mods: Update 1
to revert to version 1.5.97 or 1.6.353 until your favorite mods catch up. How to Update If you have automatic updates enabled on skyrim update 16640 new