Solution 1:
1. You can install SF3 version 1.26.1 on 1.26.0 without lose any game data.
Solution 2:
If you want to play the original game until the mod comes out you can do these steps to not lose the game data. These steps are only valid for phones with android 10 or lower:
1. Open your file manager
2. Go to android > data> and find com.nekki.shadowfight3 and rename to com.nekki.shadowfight3.bak
3. Uninstall the application and download the original version from the play store.
4. Once you have installed the game, don't open it!
5. Go back to android > data> and find com.nekki.shadowfight3.bak and rename to com.nekki.shadowfight3
6. Now open the game and play!
Once you are on the original game, you can save your progress to either the Google Play Game or Facebook.
I hope I was helpful.