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
env.cache[self][record.id] = value
    
    #
    
    #
    def _compute_value(self, records):
        """ Invoke the compute method on ``records``. """
        
        fields = records._field_computed[self]
        for field in fields:
            for record in records:
                record._cache[field] = field.convert_to_cache(False, record, validate=False)
        if isinstance(self.compute, basestring):
            getattr(records, self.compute)()
        else:
            self.compute(records)
    def compute_value(self, records):
        """ Invoke the compute method on ``records``; the results are in cache. """
        fields = records._field_computed[self]
        with records.env.do_in_draft(), records.env.protecting(fields, records):
            try:
                self._compute_value(records)
            except (AccessError, MissingError):
                
                for record in records:
                    try:
                        self._compute_value(record)
                    except Exception as exc:
                        record._cache[self.name] = FailedValue(exc)
    def determine_value(self, record):