The diffuse Function seems to be broken

[EinsMalte]

What have I done, to come to this conclusion:

1. Make all the Trail Maps public and visible in the Inspector
   
2. Disable the copy method
   
3. Look at the Render Textures in the Inspector
   Trail Map:
   
   Diffused Trail Map:
   

What are my PC Specs?
Intel(R) Core(TM) i5-9400F (6 Cores @ 2.9 GHz)
16 GB RAM
NVIDIA GeForce GT 710

(Yes my PC is a cheap Prebuilt. His name is "Potatoe")

[EinsMalte]

After some more investigating I've found out, that the originalCol isn't working out.
On line 158 the originalCol is set to the TrailMap[id.xy] and on line 174 the DiffusedTrailMap[id.xy] is set to that color.

[EinsMalte]

This works: