A revenge glow-up still has their name written on it. Glow up for you and the name disappears.

Motivation built on proving something to a specific person keeps that person in charge of the project. You are still organising your effort around their reaction, which means their indifference can flatten you and their approval becomes the finish line. The change is real and the steering is theirs.

Ask what you would still want if they never found out. Whatever survives that question is yours to keep. Build on that part, and let the rest of the motivation fall away as the months go on.