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
super(Html, self)._setup_attrs(model, name)
        
        if self.translate is True and self.sanitize:
            self.translate = html_translate
    _related_sanitize = property(attrgetter('sanitize'))
    _related_sanitize_tags = property(attrgetter('sanitize_tags'))
    _related_sanitize_attributes = property(attrgetter('sanitize_attributes'))
    _related_sanitize_style = property(attrgetter('sanitize_style'))
    _related_strip_style = property(attrgetter('strip_style'))
    _related_strip_classes = property(attrgetter('strip_classes'))
    _description_sanitize = property(attrgetter('sanitize'))
    _description_sanitize_tags = property(attrgetter('sanitize_tags'))
    _description_sanitize_attributes = property(attrgetter('sanitize_attributes'))
    _description_sanitize_style = property(attrgetter('sanitize_style'))
    _description_strip_style = property(attrgetter('strip_style'))
    _description_strip_classes = property(attrgetter('strip_classes'))
    def convert_to_column(self, value, record):
        if value is None or value is False:
            return None
        if self.sanitize:
            return html_sanitize(
                value, silent=True,
                sanitize_tags=self.sanitize_tags,
                sanitize_attributes=self.sanitize_attributes,
                sanitize_style=self.sanitize_style,
                strip_style=self.strip_style,
                strip_classes=self.strip_classes)
        return value
    def convert_to_cache(self, value, record, validate=True):