What happens when the recipient modifies/deletes the details appearing in FORM GSTR-2A?

If the recipient modifies/deletes any details, such modification/deletion will be
communicated to the supplier in FORM GSTR-1A. The supplier can accept/reject such modification/deletion before 17th of the succeeding tax period. To the extent of such modifications/ deletions, FORM GSTR-1 of the supplier would stand amended.

(ICAI FAQ PUBLICATION 06-09-2017 -: Returns : FAQ NO. 6)