Odoo17, The following settings have already been set，but the attachment file is still attached to the chatter.

1、added _mail_post_access = 'read' in model class

_inherit = ['mail.thread', 'mail.activity.mixin']
_mail_post_access = 'read'

2、added tracking=False in the field definition

op_contract_attachment_ids = fields.Many2many('ir.attachment', copy=False, tracking=False,
                                              domain=_ir_attachment_domain)

3、in the view，added widget="many2many_binary"

<field name="op_contract_attachment_ids" options="{'no_create': False}"
       readonly="not page_editable" string="" widget="many2many_binary"/>

On the contrast, the attachment file will NOT be pushed into the chatter if widget="many2many_binary" is not used in the view.

Does anyone know how to avoid pushing ir.attachment file to the chatter while using widget many2many_binary?