TDS on Previous Year (FY18-19) Invoice has been deducted in Current Year (FY19-20)

Thanks for your inputs.

Just to broader the question from vendor perspective on TDS adjustments (which is deducted by us) :

1. FY18-19 Income Tax return ~ As TDS is not deducted during the FY18-19 (only deducted in Apr’19 e. FY19-20) and the TDS will reflect in FY19-20 form 26AS, hence the vendor will not be able to adjust the TDS in their return for FY18-19. Correct me if I am wrong.
2. FY19-20 Income Tax return ~ TDS is deducted during FY19-20 (i.e. Apr.’19) and it is reflecting in form 26AS. However, considering the provisions mentioned in Income Tax Rule 35BA (3) (I) “ TDS Credit shall be given for the assessment year for which such income is assessable". In this case Income for the vendor for queried invoices are included in his Income for previous year FY18-19 and assessed accordingly.

Please advise on the best way forward, which can suggested to our vendors.