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).


odoo/fields.py
""" Base setup: things that do not depend on other models/fields. """
        if self._setup_done and not self.related:
            
            self._setup_done = 'base'
        else:
            
            self._setup_attrs(model, name)
            if not self.related:
                self._setup_regular_base(model)
            self._setup_done = 'base'
    #
    
    #
    def _can_setup_from(self, field):
        """ Return whether ``self`` can retrieve parameters from ``field``. """
        return isinstance(field, type(self))
    def _setup_attrs(self, model, name):
        """ Determine field parameter attributes. """
        
        attrs = {}
        if not (self.args.get('automatic') or self.args.get('manual')):
            
            for field in reversed(resolve_mro(model, name, self._can_setup_from)):
                attrs.update(field.args)
        attrs.update(self.args)         
        attrs['args'] = self.args