When I try to add a made up VAT number to a Belgian contact in Odoo 15, there are two errors that I encounter. Note that the “Verify VAT Numbers” setting is disabled in the Accounting configuration.

The first scenario is when I add a contact and leave the country empty and try to add a VAT number:

The VAT number [BE0123456789] for partner [Fred Johnson] does not seem to be valid. 

Note: the expected format is 'CC##' (CC=Country Code, ##=VAT Number)

In the second scenario I add a country, in my case Belgium and try saving again. Now I get the following error:

The VAT number [BE0123456789] for partner [Fred Johnson] does not seem to be valid. 

Note: the expected format is BE0477472701

Why am I getting these errors?