I have seen many questions on how to downgrade the version of WH3.
1. Open Steam
Launch the Steam client and make sure you're logged in.
2. Go to your Library
Navigate to your library and find Total War: Warhammer 3 in the list of your games.
3. Right-click the game
Right-click on Total War: Warhammer 3 in your game list and select Properties from the dropdown menu.
4. Select the Betas tab
In the properties window, click on the Betas tab. This is where you can select different versions of the game.
5. Choose a previous version
In the Betas tab, you will see a dropdown menu. Click on it to see various available versions (if older versions are supported). Select the version you want to downgrade to (usually two of the latest builds are at the bottom of the list).
6. Wait for the game to update
After you select a version, Steam will automatically start downloading the necessary files to restore the game to that version.
7. Launch the game
Once the download is complete, you can launch Total War: Warhammer 3, and it should be running the downgraded version.
Well, 5.2.6 intentionally removed previous rollbacks... Table's still broken after 5.2.5, and we can't rollback anymore (at least for a patch), so CA hit with one-two combo...