Thanks for sharing that video.
It looks like that video was rendered with Path Tracer. That flickering effect is a side effect of the denoiser that Path Tracer uses to remove the noise that is generated during a Path Tracer render. The denoiser will try its best to remove noise, but in videos, it will often leave artifacts like that flickering.
Our upcoming update to 2023.1 Preview 2 will include improvements to the video denoiser that should reduce this effect with Path Tracer renders.
There are also third-party tools, such as Neat Denoiser, Davinci Resolve's denoiser tool, and Adobe Premiere's denoiser tool that provide very good results. If you export your video with the denoiser disabled, you can use one of these third party denoisers to clean up the resulting video, usually eliminating these artifacts.
Best,
Raghib