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).


""" Write the value of ``self`` on ``records``. The ``value`` must be in
        the format of method :meth:`BaseModel.write`.
        """
        return NotImplementedError("Method write() undefined on %s" % self)
    
    #
    
    #
    def __get__(self, record, owner):
        """ return the value of field ``self`` on ``record`` """
        if record is None:
            return self         
        if record:
            
            record.ensure_one()
            try:
                value = record._cache[self]
            except KeyError:
                
                if record.id:
                    self.determine_value(record)
                else:
                    self.determine_draft_value(record)
                value = record._cache[self]
        else:
            
            value = self.convert_to_cache(False, record, validate=False)
        return self.convert_to_record(value, record)
    def __set__(self, record, value):