The final battle of tournament of Power boiled down to Jiren and Goku's battle. The aces of each universe are expected to pour all of their strength in the battle. There are only two minutes left in the battle between them; two minutes to save their own universes from erasure. This is a critical time, a single mistake will spell erasure instead of survival. But despite this very critical time, Frieza is nowhere to be found. Is he still planning for the perfect betrayal that everyone is anticipating even from the start of the tournament? Or did he lost it and will try to avenge his pride at all cost?
Is he still even alive?
Frieza and his arrogance
Frieza is known throughout the Dragon Ball history as a very confident and arrogant guy. He was born a beast, and he utilizes that knowledge to conquer planets. The Ice-jin hates to lose and will do anything to get the victory that he deserves. Because of this, he will never be fond of losing, and it will be even worse if the filthy monkey named Goku will have the kill. And as he said before, Frieza doesn't care about the rules anymore; this is evident when he tried to kill Jiren out of rage via surprise attack in which ended badly for him.
This makes Frieza's betrayal a very vague concept. After being composed and cool throughout the rest of Tournament of Power, he is now acting recklessly.
It can be remembered that when Super Saiyan Goku started to beat Frieza, his cool facade started to wear out. Because of Frieza's lack of experience for hard battles, he cannot handle the situation if he deems he is on the losing side unlike Goku and the others.
Frieza's betrayal
During the final moment of Jiren and Goku's battle, with a weakened Jiren on the edge of the arena, Goku charges his Kamehameha for the final time.
Being weakened as well, this will be Goku's last attack, and if it fails, he and the Universe 7 is done for. Just when he is about to fire the Kamehameha, Frieza will appear out of nowhere and will scream "He is mine!" before knocking out Goku.
With his signature "hohohoho" laugh, he tries to eliminate Jiren himself, but even the weakened Jiren has the power to deflect all his attacks and knock him out before the time runs out.
This is what I think will happen in the Tournament of Power, which is aligned to Frieza's personality.
This is just my theory and what I think is the most logical action for Frieza in the final moments. He may or may not betray Universe 7. But it is more likely that he would rather than not.