What is this black outline on my subviewport texture?

Godot Version

4.2.2

Question

So I have a tilemap that renders into a Subviewport. This is so a Mode-7 shader can be applied to the whole thing instead of each tile.
image
This works great, there’s a tad of latency but that’s unavoidable when dealing with Subviewports. The only real problem is that the outputted has a strange black outline, no matter what settings I turn on (within the Mobile rendering backend).
image
Anyone able to explain what’s happening here, unless it’s a bug, which in that case it should probably be patched.

So I figured out the problem here. It turns out that anisotropic filtering was causing it, I assume the black outline was it failing to apply that correctly. The fix was to just set the texture mode to Nearest Mipmap instead of Nearest Mipmap Anisotropic. Don’t know why it was failing, I can only assume it’s related to ViewportTextures but I’m not sure. Anyway, that’s all from me.

you might want to post this to the github, as it could be a bug with the rendering engine of Godot.