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
continue
            target = env[field.model_name]
            protected = env.protected(field)
            if path == 'id' and field.model_name == records._name:
                target = records - protected
            elif path and env.in_onchange:
                target = (target.browse(env.cache[field]) - protected).filtered(
                    lambda rec: rec if path == 'id' else rec._mapped_cache(path) & records
                )
            else:
                target = target.browse(env.cache[field]) - protected
            if target:
                spec.append((field, target._ids))
        return spec
class Boolean(Field):
    type = 'boolean'
    column_type = ('bool', 'bool')
    def convert_to_column(self, value, record):
        return bool(value)
    def convert_to_cache(self, value, record, validate=True):
        return bool(value)
    def convert_to_export(self, value, record):
        if record._context.get('export_raw_data'):
            return value
        return ustr(value)
class Integer(Field):