Hello
It is something like
rmgr: Heap len (rec/tot): 143/ 143, tx: 748, lsn: 0/01530AF0, prev 0/01530AB8, desc: INSERT off: 17, flags: 0x00, blkref #0: rel 1664/0/1260 blk 0
just insertion into pg_authid (oid=1260)
regards, Sergei