Why movement feels stuttering?

Example of a gameplay

According to stats (not included it in the video) the game runs at 140-150 fps. However it looks like this. Especially when i look at ground.

C# Script of FPSController

Inspector screen of FPSController

I used a free asset: https://assetstore.unity.com/packages/tools/input-management/mini-first-person-controller-174710