IBAN Mandatory for the UK - Personal Payment Methods

Summary

What do other Global companies do to solve for the fact that IBAN is a mandatory field in UK but it's not commonly known by employees?

Content

We are aware that you can turn IBAN validation off at 'site' level in Personal Payment Methods when adding a bank account. However our 'site' is at a Global level and our countries have different rules around IBANs. I.e. For most European countries this is a mandatory field and is often printed on the bank cards. However in the UK this is not a commonly used number, most online banking apps you cannot find this information. So I'd like to know how other customers are dealing with this issue in the UK?