I have come across the same problem with PCG and Megascan Trees. I am unsure of what causes the issue, but as mentioned by @lobnico the Pivot painter megascans don’t seem to cause the texture issue. Moreover, if you disable nanite on the SimpleWind trees it fixes the glitches.
This may be a megascans/wind issue as other trees, such as the Interactive Spruce Forest, work just fine. As a work around, you could use the Pivot Painter Trees and the GlobalFoliageActor to create wind/movement.
Hope this helps!