Jesus and New Testament authors repeatedly apparently talk about the Father as Jesus' God. This Biblical Unitarian article collects some examples:
I keep asking that the God of our Lord Jesus Christ, the glorious Father, may give you the spirit of wisdom and revelation, so that you may know him better.
And has made us to be a kingdom and priests to serve his God and Father– to him be glory and power for ever and ever! Amen.
Him who overcomes I will make a pillar in the temple of my God. Never again will he leave it. I will write on him the name of my God and the name of the city of my God, the new Jerusalem, which is coming down out of heaven from my God; and I will also write on him my new name.
Even in the book of Revelation (after his death, resurrection, and ascension), when Jesus has all authority in Heaven and on Earth, seated at the right hand of God, he still says “my God.”
1 Peter 1:3
Praise be to the God and Father of our Lord Jesus Christ! In his great mercy he has given us new birth into a living hope through the resurrection of Jesus Christ from the dead
John 20:17 (NASB)
Jesus said to her, “Stop clinging to me, for I have not yet ascended to the Father; but go to my brethren, and say to them, ‘I ascend to my Father and your Father, and my God and your God.’”
So that with one heart and mouth you may glorify the God and Father of our Lord Jesus Christ.
2 Corinthians 1:3
Praise be to the God and Father of our Lord Jesus Christ, the Father of compassion and the God of all comfort.
2 Corinthians 11:31 (KJV)
The God and Father of our Lord Jesus Christ, which is blessed for evermore, knoweth that I lie not.
To this can be added other verses, such as Hebrews 1:8-9.
"But about the Son He says: “Your throne, O God, endures [alt. 'Your throne is God'] forever and ever, and justice is the scepter of Your kingdom. 9 You have loved righteousness and hated wickedness; therefore God, Your God, has anointed You above Your companions with the oil of joy.”" (Berean Study Bible)
Similarly, there are passages which strongly suggest Jesus has a God, such as Luke 4:5-8.
"Then the devil led Him up to a high place and showed Him in an instant all the kingdoms of the world. 6 “I will give You authority over all these kingdoms and all their glory,” he said. “For it has been relinquished to me, and I can give it to anyone I wish. 7 So if You worship me, it will all be Yours.” 8 But Jesus answered, “It is written: ‘Worship the Lord your God and serve Him only.’”"
The assertions that Jesus has a God cut across the New Testament, including St. Peter, St. Paul, St. John, and the author of Hebrews' writings. They are made both by Jesus himself before he ascends, and by others after He ascends.
According to Trinitarian theology, does only God the Son have a God? Or does God the Father also? God the Holy Spirit? (Or are all the examples above misleading, and none of the persons of the Trinity has a God?)