Flickering/Bright sparkeling with Planar Reflection Probe and Trees (HDRP)

I have this weird flickering in my project: https://youtu.be/vKX9Nk1pt8Q

When I turn off the Planar Reflection Probe it disappears, but I need the Reflection Probe for reflection on the water. The flickering appears only in Standalone Build and not in the Editor, which is making debugging a living hell. The Planar Reflection Probe spans the entire terrain. Strangely the bright flickering effect is only on the left side of the screen and never on the right.

What I Tried:

• Disable Terrain -> no difference

• Change Material on Tress to HDRP/Lit Opaque and without any texture -> no difference

• Disable Bloom -> the flickering is not that bright anymore but is still visible

• Disable all Post Processing -> same as disabling bloom

• Disable Shadows -> no difference

• Cannot reproduce the problem in new/fresh Project :(

Informations:

• Unity 2019.4.25f1

• HDRP 7.9

• Vegetation Studio 4.9

• Planar Reflection Probe Settings: https://www.dropbox.com/s/8cfe9g4rx4eq87v/PlanarReflectionSettings.jpg?dl=0

Does anyone have an idea? I am kind of desperate and look forward to every hint.