issue_comments: 603490643

Here's a quick and dirty workaround that works at least for my use case. arr_orig is the original DataArray from which arr_unstacked_bad was generated via a stack/groupby/apply/unstack chain yielding the _level_0 etc. dims, with the stack call having been arr_orig.stack(**{dim_of_stack: dims_stacked}). Likely excessively convoluted and YMMV.

```python def fix_unstacked_dims(arr_unstacked_bad, arr_orig, dim_of_stack, dims_stacked): """Workaround for xarray bug involving stacking str-based coords.

C.f. https://github.com/pydata/xarray/issues/3287

"""
dims_not_stacked = [dim for dim in arr_orig.dims if dim not in dims_stacked]
stacked_dims_after_unstack = [dim for dim in arr_unstacked_bad.dims 
                              if dim not in dims_not_stacked]
dims_mapping = {d1: d2 for d1, d2 in zip(stacked_dims_after_unstack, dims_stacked)}
arr_unstacked_bad = arr_unstacked_bad.rename(dims_mapping)

arr_out = arr_orig.copy(deep=True)
arr_out.values = arr_unstacked_bad.transpose(*arr_orig.dims).values
return arr_out.assign_coords(arr_orig.coords)

```