Okay, here's my experience.
Started Mounjaro in August 2024 at 11st 7.8lb (BMI was 31, I also have chronic hypertension). Stopped Mounjaro at the end of December 2024 without tapering, just full cold turkey and I was 8st 11.6lb at this point.
By June I was 8st 5lb, not through trying to lose, just trying to maintain. Today I am 8st 3lb (just weighed myself as I do daily weighing!).
I've not struggled to maintain my weight loss BUT I had no underlying medical issues that caused me to gain weight, and I had no food issues either. If we're being brutally honest, I was overweight because I ate and drank way more than I should have, and I was lazy. This is what I've turned around for myself.
I never miss my daily step goal as it makes sure I am moving - I work from home a lot and without forcing myself to move, I'd average around 2,000 steps a day. I watch what I eat, to an extent, but I don't calorie count and I drink plenty of wine - I'm just hyper aware that if I am going out for dinner for example, I eat lighter through the day. I don't eat takeaways as I'm no longer fussed about them, and I've stopped eating food like pizza and pasta which I found had a negative effect on me. I crave vegetables so my diet is very heavy on vegetables with chicken or fish. I'm just more mindful generally about what I am putting into my body - I survived an all-inclusive holiday this summer and came back weighing exactly what I was before I left, but ultimately I love to eat, I've just changed what it is I eat.
So no, it's not confirmed that you need to be on jabs for life BUT I think it's highly dependant on the reasons you were overweight in the first place (which isn't always that straightforward), the relationship you have with food, and the healthy habits that you put in place while you are using the medication.
ETA: I went into it knowing I didn't want to be on it for life - I'm already on lifelong medication, I didn't want another. I wanted to lose the weight, and reset.