Downpatch to patch #2 (3.0.143.909) instructions:

1. Copy Classic folder into your DOS2 install dir

To find this, right click 'Divinity Original Sin 2' in your Steam library, and click properties
Click 'local files', then browse local files...
Either copy the 'Classic' folder in this .zip into this folder, or drag all the files from that folder into your 'Classic' folder
DO NOT PUT THESE FILES INTO YOUR BIN FOLDER, THEY GO IN THE CLASSIC FOLDER

2. In the Data folder of your DOS2 install dir, delete all Patch*.pak files EXCEPT Patch.pak and Patch2.pak
The files you SHOULD delete as of patch 5 are:
Data\Patch3.pak
Data\Patch4.pak
Data\Patch4_1.pak
Data\Patch4_hotfix.pak
Data\Patch4_hotfix2.pak
Data\Patch5.pak
Data\Patch5_1.pak
Data\Patch5_2.pak
Data\Patch5_hotfix1.pak
Data\Patch5_hotfix2.pak
Data\Patch6.pak
Data\Patch6_hotfix1.pak
Data\Patch6_hotfix2.pak
Data\Patch7.pak
Data\Patch7Hotfix1.pak
Data\Patch8.pak

3. Note that every time Divinity updates even though it is only updating the Definitive edition, it usually will re-download the Classic exe and DLLs, and also all the patches
So when the game does update make sure all the patches are gone, and re-downpatch the game if they're not