John the Baptist wrote the first Apocalypse but this command was for John the Apostle who wrote the second adding the churches, Jesus, Antipas etc.  Based on Acts 19 there were Baptist followers in Ephesus who did not know or accept Jesus so the Apostle redid the Apocalypse to get their attention.

to show his servants – plural – more than one – in the same verse His servant – singular – John is introduced – that is – John the Baptist to testify and to the testimony

this is the first John – the first servant – who knew the Lamb of God but not Jesus – who knew the seven spirits but not the seven churches

Watch for more pieces that fit.  Blessed is the one who looks.

John the Baptist to testify and to the testimony

John the Apostle to the seven churches

John Chrysostom your brother

Watch for more pieces that fit.  Blessed is the one who looks.