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

addons/account/account_invoice.py
recs = self.browse(cr, uid, [], context)
        invoice = recs.env['account.invoice'].browse(invoice_id)
        return account_invoice_tax.compute(recs, invoice)
    @api.model
    def move_line_get(self, invoice_id):
        res = []
        self._cr.execute(
            'SELECT * FROM account_invoice_tax WHERE invoice_id = %s',
            (invoice_id,)
        )
        for row in self._cr.dictfetchall():
            if not (row['amount'] or row['tax_code_id'] or row['tax_amount']):
                continue
            res.append({
                'type': 'tax',
                'name': row['name'],
                'price_unit': row['amount'],
                'quantity': 1,
                'price': row['amount'] or 0.0,
                'account_id': row['account_id'],
                'tax_code_id': row['tax_code_id'],
                'tax_amount': row['tax_amount'],
                'account_analytic_id': row['account_analytic_id'],
            })
        return res
class res_partner(models.Model):