How to improve the stabilization and smooth of video from Thumb?

Except using a mount to reduce jitter, a software-GyroFlow could also help.

(Tip:Please use GCsv in the configuration file to open the gyroscope data. It is recommended to use a high-speed card above 64G, and the resolution is set to 1080p@50fps;)

Please update the firmware of Thumb to V2.1.0, and also update Gyroflow to V1.0.0-RC5 (at least).
Pay attention to the setting of Low pass filter, please set as 43Hz.
And also tick the Rolling shutter correction at the right side.