21 When all the people were being baptized, Jesus was baptized too. And as he was praying, heaven was opened 22 and the Holy Spirit descended on him in bodily form like a dove. And a voice came from heaven: “You are my Son, whom I love; with you I am well pleased.”
(Luke 3:21-22)
A better translation is the following:
And all the people arrived in being baptized ἐν τῷ βαπτισθῆναι , and Jesus having been baptized and praying, heaven was opened and the Holy Spirit was descended
Luke doesn't say expliciter that Jesus was baptized by John. He doesn't say that Jesus was baptized by the disciples of John.
Therefore Jesus baptized himself in that episode, and all the people baptized themselves, not by John, but BEFORE John.
Luke doesn't call John as "the Baptizer" (Luke 3:3-4). Therefore for him John doesn't baptize. He leaves the people baptize themselves before him and not by him.
Codex Bezae (D) reads: "He said to the people came to be baptized before him (enopion autou) " and not "baptized by him" (hup'autou).
The reading "before him" is more primitive than "by him".
Always Luke, puts the arrestation of John before the presumed baptism of Jesus to avoid to say that Jesus was baptized by John.
This baptism of Jesus by himself fits perfectly the Corpus Hermeticum 4:4:
"Baptize yourself". Implicit: "by yourself".