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).


comodel = records.env[self.comodel_name].with_context(**self.context)
        inverse = self.inverse_name
        domain = self.domain(records) if callable(self.domain) else self.domain
        domain = domain + [(inverse, 'in', records.ids)]
        lines = comodel.search(domain, limit=self.limit)
        
        group = defaultdict(list)
        for line in lines.with_context(prefetch_fields=False):
            
            group[int(line[inverse])].append(line.id)
        
        for record in records:
            record._cache[self.name] = tuple(group[record.id])
    def write(self, records, value):
        comodel = records.env[self.comodel_name].with_context(**self.context)
        inverse = self.inverse_name
        with records.env.norecompute():
            for act in (value or []):
                if act[0] == 0:
                    for record in records:
                        act[2][inverse] = record.id
                        comodel.create(act[2])
                elif act[0] == 1:
                    comodel.browse(act[1]).write(act[2])
                elif act[0] == 2: