Video Rendering flickering problem

Problem: After editing some footages on the Drone, the video editing features some flickers in some of the closest images.

The footage was taken at 3840x2160 4k 24 fps, iso 100 shuteer 50, with ND32. The image stream is very cinematic and smooth.

when rendering with some adjustments in contrast and brigtness, some closer footages, the video is flickering in a contant approx. 1 second time rate. If objects are further away, the problem does not exist.

I’ve tried doing some tests with the bit rate change and rate control, and the problems do occur.
Any help will be appreciated.

Resolution: 3840x2160
Aspect Ratio: 16: 9
Frames: 24
Scan Mode: Progressive

Codec: libx264
Rate Control: Constant Bitrate
Bit Rate: 140M
Buffer: 224
GOP: 12
B Frame: 2

Thank you

Alfredo Santos