As TpacTool has been broken by the latest update, the best approach for Steam users to continue using it is as follows:
1. Without activating Steam, reename your ...\Documents\Mount and Blade II Bannerlord folder to say \Documents\Current_Mount and Blade II Bannerlord then rename your C:\Program Files (x86)\Steam\steamapps\common\Mount & Blade II Bannerlord folder to C:\Program Files (x86)\Steam\steamapps\common\Current_Mount & Blade II Bannerlord
2. Activate Steam, go to Bannerlord in your library, right click on it and select properties, then on the betas tab from the drop down list select e1.4.1_e1.4.1
As you renamed your local folders in 1 above Steam will install a full version of e1.4.1 without affecting them.
3. After the old version has downloaded, switch off Steam then rename the newly installed ...\Documents\Mount and Blade II Bannerlord folder to say \Documents\Old_Mount and Blade II Bannerlord then rename your C:\Program Files (x86)\Steam\steamapps\common\Mount & Blade II Bannerlord folder to C:\Program Files (x86)\Steam\steamapps\common\Old_Mount & Blade II Bannerlord
Redirect TpacTool to load C:\Program Files (x86)\Steam\steamapps\common\Old_Mount & Blade II Bannerlord\Modules\Native\AssetPackages
4. Without activating Steam, reename your ...\Documents\Current_Mount and Blade II Bannerlord folder back to \Documents\Mount and Blade II Bannerlord then rename your C:\Program Files (x86)\Steam\steamapps\common\Current_Mount & Blade II Bannerlord folder back to C:\Program Files (x86)\Steam\steamapps\common\Mount & Blade II Bannerlord
This allows you to play the current game loaded from your desktop icon and keep an old version locally for TpacTool to access AssetPackages. You will not be able to access any new armours etc., but I believe very little has changed even though the whole AssetPackages folder was updated due to the nature of TW's optimised compression.
Next time you switch on Steam reset the beta tab to the current game or it will try to overwrite your current version with the older one you downloaded for TpacTool access.
Hopefully, that approach will help until
@szszss updates her wonderful tool.
PS if you have limited disk space, you could experiment with deleting other folders unlikely to be required by AssetPackages in your old archive version. I haven't tried this, but doubt TpacTool needs much more than the AssetPackages and TileSets folders. Rather than deleting other folders rename them with an x in front intially to see if TpacTool works without them. Please let us know what can be culled without affecting TpacTool.