Hi FirmFeet, thanks for reaching out and providing a screenshot.
The vertical stripes you are seeing are a known issue that's usually caused by the "Twinkling Stars" option from the VanillaTweaks resource pack. Unfortunately, I'm unable to fix this directly from Wurst's end. However, you can resolve this issue by either disabling VanillaTweaks or re-downloading it without the "Twinkling Stars" option.
Normally, Wurst should display a warning in chat whenever it detects this resource pack being used. If you didn't see this warning or if you're using a different resource pack that's causing this issue, please let me know so I can update future warnings accordingly.
Hope this helps!