Psalm 34:7 says, “The angel OF Yahweh encamps around those who fear Him, and rescues them.”
I first heard the Trinitarian argument that a pre-incarnate angel was the alleged pre-incarnate, omnipresent Son of God who encamps around the righteous in one of Sam Shamoun’s debates posted on YouTube. First of all, the text reads, “The angel OF Yahweh” and not Yahweh Himself; so the angel OF Yahweh could not be Yahweh Himself. Secondly, there is not a single scripture anywhere in the Bible that ever says that any of the angels are omnipresent. Thirdly, Psalm 34:7 does not imply that only one specific angel OF Yahweh encamps around those who fear God.
The Pulpit Commentary says, “... the expression, “angel of the Lord,” is here used as a collective, and means the angels generally. With this certainly agrees the statement that the angel “encampeth round about them that fear him;” and the illustration from 2 Kings 6:14-18 is thus exactly apposite” (relevant).
The Pulpit Commentary continues, “But others deny that “the angel of the Lord” has ever a collective sense, and think a single personality must necessarily be intended, which they regard as identical with “the captain OF Jehovah’s host” [the captain OF Jehovah’s host could not be Jehovah],” who appeared to Joshua (Joshua 5:14, 15), and “the angel of the Lord's presence” spoken of by Isaiah (Isaiah 63:9) … When pressed to say how this one angel can “encamp round” a number of persons, they reply that, of course, he has his subordinates with him - a “spangled host,” that “keep watch in squadrons bright;” and that he is said to do what they do, which is no doubt quite in accordance with ordinary modes of speech. Thus, however, the two expositions become nearly identical, since, according to both, it is the angelic host which “encamps around” the faithful.”
Fourthly, Psalm 99:1 says, “He sits between the CHERUBIM”. The text does not say, cherubim’s in the plural, but “cherubim” in the singular. Therefore God’s angels can be spoken of as “the angel of the LORD” in a collective sense.