Merge pull request #21857 from BastiaanOlij/fix_never_true_prealpha

Fixed a theoretical condition where prealpha prevents lighting

drivers/gles3/rasterizer_canvas_gles3.cpp

@@ -1418,7 +1418,7 @@ void RasterizerCanvasGLES3::canvas_render_items(Item *p_item_list, int p_z, cons
 		if (blend_mode == RasterizerStorageGLES3::Shader::CanvasItem::BLEND_MODE_DISABLED && (!storage->frame.current_rt || !storage->frame.current_rt->flags[RasterizerStorage::RENDER_TARGET_TRANSPARENT])) {
 			blend_mode = RasterizerStorageGLES3::Shader::CanvasItem::BLEND_MODE_MIX;
 		}
-		bool unshaded = shader_cache && (shader_cache->canvas_item.light_mode == RasterizerStorageGLES3::Shader::CanvasItem::LIGHT_MODE_UNSHADED || blend_mode != RasterizerStorageGLES3::Shader::CanvasItem::BLEND_MODE_MIX);
+		bool unshaded = shader_cache && (shader_cache->canvas_item.light_mode == RasterizerStorageGLES3::Shader::CanvasItem::LIGHT_MODE_UNSHADED || (blend_mode != RasterizerStorageGLES3::Shader::CanvasItem::BLEND_MODE_MIX && blend_mode != RasterizerStorageGLES3::Shader::CanvasItem::BLEND_MODE_PMALPHA));
 		bool reclip = false;
 
 		if (last_blend_mode != blend_mode) {