You must IPv6 completely. Using '2a01:4f8:120:134d:0:0:0:2' instead '2a01:4f8:120:134d::2'
Done, but nothing is found:
NOTICE: While reading domain NS records at parent name servers, we found name servers without AAAA records.
ns1.xxx.pl. ? ?
ns2.xxx.pl. ? ?
ns3.xxx.pl. ? ?
To reach your name servers via IPv6 an AAAA record is needed for each name server.