Location cards are rendered incorrectly

[sebastientromp]

(putting it here so that there is a single place I can refer to).

This is what the final location card looks like.
The way I render cards is to load them up in Unity, then take a screenshot:

public IEnumerator CaptureScreenshot(
            GameObject targetObject, string destPath, int width = 500, int height = 650, int targetWidth = 512, int startX = 617, int startY = 310)
        {
            yield return new WaitForEndOfFrame();
            captureCamera.cullingMask = 1 << targetObject.layer; // Only render the layer the target object is on

            RenderTexture renderTexture = new RenderTexture(Screen.width, Screen.height, 24);
            captureCamera.targetTexture = renderTexture;
            captureCamera.Render();

            RenderTexture.active = renderTexture;
            Texture2D tex = new Texture2D(width, height, TextureFormat.ARGB32, false);
            Rect rex = new Rect(startX, startY, Math.Min(Screen.width - startX, width), Math.Min(Screen.height - startY, height));
            tex.ReadPixels(rex, 0, 0);
            tex.Apply();

            // Calculate new height to maintain aspect ratio
            float aspectRatio = (float)height / width;
            int targetHeight = Mathf.RoundToInt(targetWidth * aspectRatio);

            // Scale the captured texture
            Texture2D scaledTex = ScaleTexture(tex, targetWidth, targetHeight);

            var bytes = scaledTex.EncodeToPNG();
            File.WriteAllBytes(destPath, bytes);

            // Clean up
            captureCamera.targetTexture = null;
            RenderTexture.active = null;
            Destroy(renderTexture);
            Destroy(scaledTex);
            Destroy(tex);
        }

When the object is displayed in-game, it looks correct, with all its parts properly rendered, but the issue comes when rendering it to a texture with transparency.
If, instead of TextureFormat.ARGB32 I use a format without transparency, like TextureFormat.RGB24, it renders correctly (though obviously without a transparent background, which is an issue).

Moreover, looking at the texture files, this is what it looks like with the alpha channel off:

When turning the alpha channel on:

The missing part clearly corresponds to the part in the texture where the alpha channel is set.

So what I'm looking for now is:

• can I turn off transparency altogether in my game objects?
• since this happens only when rendering to a texture, and not with the in-game camera, maybe there is a way to tune the camera to ignore this transparency setting (but while keeping the transparent background).

[sebastientromp]

There are also other smaller transparency issues, which are assumed are linked. Putting the image against a red background reveals them quite clearly:

See this as well to reveal the transparent edges (thanks vGhost!):