John Gill Commentary Revelation 5:10

"and madest them [to be] unto our God a kingdom and priests; and they reign upon earth." — Revelation 5:10 (ASV)

And have made us unto our God kings and priests
(See Gill on Revelation 1:6). The Alexandrian copy, and Complutensian edition, and the Syriac, Arabic, and the Ethiopic versions, read "them", instead of "us":

and we shall reign on the earth ;
meaning not merely in a spiritual sense, through grace reigning over sin and corruption, through Satan being bruised under their feet, and through the victory they have in Christ over the world, but in the millennium state, in the thousand years' reign with Christ in the new earth, wherein dwelleth righteousness; see (Revelation 20:4–6) . The Alexandrian copy, and the Complutensian edition, Syriac and Arabic versions, read "they shall reign".