Impacted versions:

At least 8.0

Steps to reproduce:

See https://youtu.be/kmXVzf3ApaM

Current behavior:

Currently if you validate an invoice (even with an invoice date) after the initial conversion rate has changed
(if the rate is changed between creation and validation). The tax amount and the credit/debit amount is not computed from the same rate.

This one is responsible for several production issues for tax reporting for the fiscal administration.

Expected behavior:

The tax amount and the credit/debit amount must be computed from the same rate.

Video/Screenshot link (optional):

https://youtu.be/kmXVzf3ApaM

Related issue : https://github.com/odoo/odoo/issues/13473

My proposal to fix this one : https://github.com/odoo/odoo/pull/13621

fposition_id=False, price_unit=False, currency_id=False, company_id=None):
        context = self._context
        company_id = company_id if company_id != None else context.get('company_id', False)
        self = self.with_context(company_id=company_id)
        result = self.product_id_change(
            product, uom, qty, name, type, partner_id, fposition_id, price_unit,
            currency_id, company_id=company_id,
        )
        warning = {}
        if not uom:
            result['value']['price_unit'] = 0.0
        if product and uom:
            prod = self.env['product.product'].browse(product)
            prod_uom = self.env['product.uom'].browse(uom)
            if prod.uom_id.category_id != prod_uom.category_id:
                warning = {
                    'title': _('Warning!'),
                    'message': _('The selected unit of measure is not compatible with the unit of measure of the product.'),
                }
                result['value']['uos_id'] = prod.uom_id.id
        if warning:
            result['warning'] = warning
        return result
    @api.model
    def move_line_get(self, invoice_id):