1. `copy_cache` in `models.py` recursively copies the caches to environment, 
2. which in
```python
def _compute_related(self, records):
        """ Compute the related field ``self`` on ``records``. """
        others = records.sudo() if self.related_sudo else records
        if records.env != others.env:
            copy_cache(records - records.filtered('id'), others.env)
        values = list(others)
        for name in self.related[:-1]:
            values = [first(value[name]) for value in values]
        for record, value in zip(records, values):
            record[self.name] = value[self.related_field.name]
```
3. copies failing cache values that have been produce previously by this line:

`models.py : def _prefetch_field()`
```python

        try:
            # THIS ONE
            result = records.read([f.name for f in fs], load='_classic_write')
        except AccessError:
            # not all records may be accessible, try with only current record
            result = self.read([f.name for f in fs], load='_classic_write')
```
I checked it's exactly the same `FailedValue` object, which is later accessed without intent (not refreshed) by the fact that the buggy environment is copied to sudo (and not refreshed).


super(MetaField, cls).__init__(name, bases, attrs)
        if cls.type and cls.type not in MetaField.by_type:
            MetaField.by_type[cls.type] = cls
        
        cls.related_attrs = []
        cls.description_attrs = []
        for attr in dir(cls):
            if attr.startswith('_related_'):
                cls.related_attrs.append((attr[9:], attr))
            elif attr.startswith('_description_'):
                cls.description_attrs.append((attr[13:], attr))
class Field(object):
    """ The field descriptor contains the field definition, and manages accesses
        and assignments of the corresponding field on records. The following
        attributes may be provided when instanciating a field:
        :param string: the label of the field seen by users (string); if not
            set, the ORM takes the field name in the class (capitalized).
        :param help: the tooltip of the field seen by users (string)
        :param readonly: whether the field is readonly (boolean, by default ``False``)
        :param required: whether the value of the field is required (boolean, by
            default ``False``)
        :param index: whether the field is indexed in database (boolean, by
            default ``False``)
        :param default: the default value for the field; this is either a static