Jesus is referring to his Father and God, the Almighty, the Most High God and creator of all that is, Yahweh. Some believe Jesus is also God and this requires various ideas to make the bible work to support such a construct, but must ignore such verses (of which there are many) as Rev 3:12
There are many theories about why Jesus - who is alleged to be the eternal, immortal God himself as, 'God the Son', has a God. Some may quote John 20:28; Titus 2:13; 2 Peter 1:1, Matt 1:23 but they are readily explained better in the context of Jesus being a man who God sent into the world. Some are plainly misquoted/misinterpreted.
Let's look at some of these 'proof-texts';
Matt 1:23 “Behold, the virgin will be with child and will give birth to a son, and they will call Him Immanuel” (which means, “God with us”).
In Isaiah we read of a similar story about a promised child (not from a virgin) who was given a name of Maher-shalal-hash-baz, and a title of Immanuel. Was this child God? NO, not a chance. Is Jesus God because he was given the same title? No. Clearly though, God is and was with us in the form and image of Himself - the son Jesus who was without sin and holy in every sense. But Jesus came to die - not just a human nature, while somehow the immortal Son, who cannot die, lived on in 'heaven'! We must query God if He sent His only son or just a human copy.
Titus 2:13 looking for the blessed hope and the appearing of the glory of our great God and Saviour, Christ Jesus.
The subject is the 'glory of God' - Jesus is the GLORY of our great God. Heb 1:3, John 1:4. Does this glory make Jesus God? No.
2 Peter 1:1 To those who have received a faith of the same kind as ours, by the righteousness of our God and Saviour, Jesus Christ
That looks pretty solid! Never mind there is dispute over where to put the comma so it reads like this, 'the righteousness of our God, and Saviour Jesus Christ'
Let's just read the next verse. They are treated separately like an overwhelming number of passages including the OP verse.
Grace and peace be multiplied to you in the knowledge of God and of Jesus our Lord
That's the trouble with solitary 'proof-texts' when read out of context. However, when read with the support of other scripture, they are understood to say often the opposite of what they were proclaimed to teach.
The OP text is one of many that show Jesus, the Lamb, once risen, ascended, exalted is still not God. If he was before an incarnation, he is not anymore. If he is required to be equal to God in all things, the bible never reveals this.
We must ask, why, if Jesus is declared Lord and Christ, heir to all things, granted life by his Father and God, given the Holy Spirit, gave up his spirit at death to the Father, died in the flesh and remained dead for 3 days, raised in the spirit… how can he be God?
Jesus has a God - the same God as all of us (John 20:17) was made like one of us (Heb 2:17) tempted like us (Heb 4:15, Luke 4:2) had his own will which differed from the Father. If he is like this, he cannot be God.
Jesus gives glory to the Father and his God at every turn, every moment of his life was as a humble and obedient servant to God. If some say Jesus must be God because he is worshipped or can forgive sin etc., they are ignoring the context that fully explains the facts of God's inspired word.
As Paul and all the other NT writers understood and proclaimed consistently,
there is but one God, the Father, from whom all things came and for whom we live; and there is but one Lord, Jesus Christ. 1 Cor 8:6