Effect Reflection like water

I have a problem using the reflection effect

https://drive.google.com/file/d/1It2wqCa1_dXuSE1E9_x12KUKJIED8ePY/view?usp=drivesdk

Initially reflection was going pretty well but a few minutes later it got messy afterwards

before, reflection so smooth
https://drive.google.com/file/d/1IfGg-4u_yC_h4jz8ZptBDpKTAgWfQt6z/view?usp=drivesdk

after, reflection like pixelated
https://drive.google.com/file/d/1IgLSaELHGOY3yyn7UqS2v28WpGHFDuy0/view?usp=drivesdk

please help me and sorry for my bad language