Variious tests fail on x86 (32-bit issues)?

What happened?

FAILED xarray/tests/test_formatting.py::TestFormatting::test_diff_datatree_repr_equals - assert "Left and right DataTree objects are not equal\n\nData at node 'node' does not match:\n    Differing dimensions:\n        (y: 2) != (x: 1, y: 2)\n    Differing data variables:\n    L   data     (y) i...
FAILED xarray/tests/test_formatting.py::test_repr_pandas_multi_index - assert "<xarray.DataArray 'x' (x: 4)> Size: 16B\n[4 values with dtype=object]\nCoordinates:\n  * x        (x) object 16B MultiIndex\n  * foo      (x) object 16B 'a' 'a' 'b' 'b'\n  * bar      (x) int64 32B 1...
FAILED xarray/tests/test_coding_times.py::test_decode_timedelta_via_units[decode_timedelta=False] - AssertionError: assert dtype('int32') == dtype('int64')
FAILED xarray/tests/test_variable.py::TestVariable::test_reduce_keepdims - AssertionError: Left and right Variable objects are not identical
FAILED xarray/tests/test_groupby.py::test_groupby_reduce_dimension_error - AssertionError: Left and right DataArray objects are not identical
FAILED xarray/tests/test_groupby.py::TestDataArrayGroupBy::test_groupby_reduce_keep_attrs[None-True] - AssertionError: Left and right DataArray objects are not identical
FAILED xarray/tests/test_groupby.py::TestDataArrayGroupBy::test_groupby_reduce_keep_attrs[None-False] - AssertionError: Left and right DataArray objects are not identical
FAILED xarray/tests/test_groupby.py::TestDataArrayGroupBy::test_groupby_reduce_keep_attrs[True-True] - AssertionError: Left and right DataArray objects are not identical
FAILED xarray/tests/test_groupby.py::TestDataArrayGroupBy::test_groupby_reduce_keep_attrs[True-False] - AssertionError: Left and right DataArray objects are not identical
FAILED xarray/tests/test_groupby.py::TestDataArrayGroupBy::test_groupby_reduce_keep_attrs[False-True] - AssertionError: Left and right DataArray objects are not identical
FAILED xarray/tests/test_groupby.py::TestDataArrayGroupBy::test_groupby_reduce_keep_attrs[False-False] - AssertionError: Left and right DataArray objects are not identical
FAILED xarray/tests/test_namedarray.py::test_fake_target_chunksize[input_array0-1024-int64] - AssertionError: assert dtype('int32') == <class 'numpy.int64'>
FAILED xarray/tests/test_namedarray.py::test_fake_target_chunksize_cftime - assert 146 == 73
FAILED xarray/tests/test_dataset.py::TestDataset::test_to_and_from_dataframe - assert False
FAILED xarray/tests/test_strategies.py::TestReduction::test_mean - AssertionError: 
========================================================= 15 failed, 12970 passed, 6493 skipped, 26 xfailed, 9 xpassed, 12 warnings in 178.95s (0:02:58) ==========================================================
 * ERROR: dev-python/xarray-2025.11.0::gentoo failed (test phase):
 *   pytest failed with python3.13

Seems to be bad hardcoded assumptions? Tests all pass on amd64.

Verbose log: xarray-2025.11.0:20251128-074341.log

Steps to reproduce

In an x86 Gentoo container:

emerge --onlydeps --with-test-deps dev-python/xarray
FEATURES=test emerge dev-python/xarray

MVCE confirmation

• Minimal example — the example is as focused as reasonably possible to demonstrate the underlying issue in xarray.
• Complete example — the example is self-contained, including all data and the text of any traceback.
• Verifiable example — the example copy & pastes into an IPython prompt or Binder notebook, returning the result.
• New issue — a search of GitHub Issues suggests this is not a duplicate.
• Recent environment — the issue occurs with the latest version of xarray and its dependencies.

Environment

Reproduce the failures in the x86 Gentoo container and inspect the verbose log first. Compare the failing tests in test_formatting.py, test_coding_times.py, test_variable.py, test_groupby.py, test_namedarray.py, test_dataset.py, and test_strategies.py with their expected dtype, size, and representation assumptions. Done means the test suite passes on 32-bit Python while retaining the existing amd64 behavior.