Please try creating a new project as well and testing this plugin there.
If it works correctly in a clean project in RPG maker MZ, then the issue is most likely caused by one of the plugins in your project that affects FPS or graphics rendering.
Viewing post in Animate a tree without drawing (RPG Maker MZ) comments
The problem is not your plugin — on its own, it works perfectly, very much so. The issue is caused by two other plugins I use: one for Perfect Pixel and another for Perfect Camera. They modify the RPG Maker’s default rendering and camera behavior, which ends up causing this problem. Since the entire concept of the game is based on pixel art, unfortunately I won’t be able to use it, because when I saw your system, I truly fell in love with it.
Unfortunately, no — the plugin does not support RPG Maker MV.
It was made specifically for RPG Maker MZ and uses MZ features and architecture (such as MZ plugin commands and Scene/Interpreter behavior), so it will not work in MV.
I am still just getting started with plugin development. I have been learning MZ and I like working with it so far, but I do not yet know whether I will continue developing plugins in the long term.