Deprecation warning in GDF (and maybe more?) about yt HOT 3 CLOSED

Nice catch ! I didn't know about -X dev, looks very useful !
I think you're right that changing the signature of get_box_grids_level would fix it, but I think it would also make the code less clear, so I'd prefer to fix the call sites instead if we can.
Something like

diff --git a/yt/frontends/gdf/data_structures.py b/yt/frontends/gdf/data_structures.py
index 1bb7a88b6..0817c2aa1 100644
--- a/yt/frontends/gdf/data_structures.py
+++ b/yt/frontends/gdf/data_structures.py
@@ -115,7 +115,7 @@ class GDFHierarchy(GridIndex):
             get_box_grids_level(
                 self.grid_left_edge[gi, :],
                 self.grid_right_edge[gi, :],
-                self.grid_levels[gi],
+                self.grid_levels[gi].item(),
                 self.grid_left_edge,
                 self.grid_right_edge,
                 self.grid_levels,

from yt.

Ah, trying to fix callsites I found that this was already partially done in #4422
Mostly likely, the difference is that some call sites, as the one you found, are not covered by tests.

from yt.

I didn't know about -X dev, looks very useful !
Ya, I didn't know about it either! but was looking for an easy way to trigger the deprecation warning for sake of reproducing it since this test isn't covered by a pytest test.

from yt.