A common problem when using materials that are made for Unity3D pre-URP is that some materials converted using the Edit > Render pipeline > Convert Materials user function is they don’t convert properly at all. This can be frustrating, particularly for new users but a few clicks in most cases can restore your materials to an extent.
In this example I am using the Ivy procedural generator which I had to re-create new materials, re-assign the texture to the plants but noticed the materials are blacked on the edges.
The reason why can be explained easily by referring to the Unity documentation:
As an example I have uploaded a short video to show how easily this can be fixed inside Unity and sometimes some manual user intervention is required to convert materials over successfully to URP.