I don't think this is a bug... the gird is "inside" the cube, so if you draw anything, the final stroke will go "inside".

@Clément Foucault (fclem) Any comment about that?

@Antonio Vazquez (antoniov) An example of how I expected it to work can be seen in this recent tutorial by Dedouze. As seen in the video, the canvas drawing plane has xray. This is how it works in 2.82. In 2.83 it is not working like this and is hidden by objects making it difficult to see how the plane is oriented.
https://youtu.be/c57qq2nE3B0?t=970

It defeats the purpose of the canvas plane as a tool that assists with drawing. If we don't want to see it we can just uncheck it from the outlines dropdown and drawing still works the same. The point of this ticket is, when we enable canvas, we cannot see it anymore in 2.83 if it is covered by objects in the scene.

To add to this, Actually it would be nice to have a toggle for xray. If xray is disabled, it might help us visually when trying to align the plane to object surfaces. But in general use, i think i would keep xray ON since it is a helper tool

@Clément Foucault (fclem) I think that we could disable depth test for Grid Canvas....

diff --git a/source/blender/draw/engines/overlay/overlay_gpencil.c b/source/blender/draw/engines/overlay/overlay_gpencil.c
index b79d5753686..1620de85a28 100644
--- a/source/blender/draw/engines/overlay/overlay_gpencil.c
+++ b/source/blender/draw/engines/overlay/overlay_gpencil.c
@@ -256,7 +256,7 @@ void OVERLAY_gpencil_cache_init(OVERLAY_Data *vedata)
     const int gridlines = (gpd->grid.lines <= 0) ? 1 : gpd->grid.lines;
     int line_ct = gridlines * 4 + 2;
 
-    DRWState state = DRW_STATE_WRITE_COLOR | DRW_STATE_DEPTH_LESS_EQUAL | DRW_STATE_BLEND_ALPHA;
+    DRWState state = DRW_STATE_WRITE_COLOR | DRW_STATE_BLEND_ALPHA;
     DRW_PASS_CREATE(psl->gpencil_canvas_ps, state);
 
     sh = OVERLAY_shader_gpencil_canvas();

What do you think?

@Matias Mendiola (mendio) @Daniel Martinez Lara (pepeland) Do you think the grid must be always on top?

There is an X-ray toggle but in Solid Viewport shading working right now
but not in Material Preview or Rendered Viewport shading.

I don't like to add more switches or reuse X-Ray button. This button is for other things and it's not separated for grid only, so it's not a good solution.

IMHO the best solution is just keep on top all the time as an overlay. Also, we have the opacity of the grid, so if keeping on top is too intrusive, the artist can reduce opacity to get a better experience.

@Antonio Vazquez (antoniov) I just found this thread as I was also following Dedouze's tutorial and was confused when the canvas was occluded by the cube. I suspect many people would prefer that the canvas is always visible on top even when X-Ray is disabled, would it be possible to add a toggle option to the Viewport Overlays drop-down?

@Matias Mendiola (mendio) @Daniel Martinez Lara (pepeland) Do you think is good idea add an option to set the Grid on top?

A toggle would be good because there may be situations where we do and do not want it on top.

Proposed new option in D7721