Fall Guys game does not support the resolutions of the Ultrawide (21: 9) and Super Ultrawide (32: 9) monitors for now.
We had the same issue in Code Vein, it is possible to solve this problem in Fall Guys with the same method.

How to fix Ultra-widescreen resolution issues on Fall Guys?
We will fix the resolution problem in Fall Guys by changing the codes in the dll file of the game using a simple software.
- Download and install the HxD Hex Editor
- Launch it.
- Press Ctrl + O keys
- Select and open the UnityPlayer.dll file (...\SteamLibrary\steamapps\common\Fall Guys)
- Press Ctrl + R keys
- Go to Hex-values tab
- Enter 39 8E E3 3F into the "Search for" text box.
39 8E E3 3F
- For example, for the 3440x1440 resolution, enter 8E E3 18 40 into the "Replace with" text box.
8E E3 18 40

- Make sure that "All" is selected in the "Search direction" section
- Then press the "Replace all" button.
- Now, save by pressing Ctrl + S keys
- Exit the application.
- That's all, play the game!
Note: If you experience a problem after these changes, delete the UnityPlayer.dll file and verify the file integrity of the game on Steam.
16:10 (1440x900, 1680×1050)
CD CC CC 3F
21:9 (2560x1080)
26 B4 17 40
21:9 (3440x1440, 5120x2160)
8E E3 18 40
21:9 (3840x1600)
9A 99 19 40
32:9 (3840x1080, 5120x1440)
39 8E 63 40
32:9 (3840x1440)
AB AA 2A 40
32:10 (3840×1200, 5120×1600)
CD CC 4C 40

Not working, i cant FIND this 39 8E E3 3F in this file :C always “NOT FOUND: 39 8E E3 3F”
bro help for resolution 1260×1024
Bro help I need 1280×1024
Try this: 00 00 A0 3F
Doesn’t this ban me?
no guarantee, at your own risk
não consigo deixar 1024×768 🙁
1440×900 ı cant find can u guys help me
I have updated the guide.
use this: CD CC CC 3F
What code should I use for 1680×1050
CD CC CC 3F
Thank you so much! 🙂
happy to help