I lost about 15-20 kg on Ozempic over about six months to a year, and held that weight for another year – continuing on 1 mg Ozempic / wk – until last autumn (2022). Then Ozempic was more widely approved than it had been before somewhere (for over-the-counter sales in the USA? Something like that.), and became unavailable in pharmacies where I live, in Finland. (AIUI, because it's more lucrative to sell it in the USA where prices aren't regulated like here, so all the limited supply is redirected there.) No problem, I was prescribed a substitute, a daily pill (brandname Rybelsus, forgot the active substance) in stead of the weekly injection pen. Worked the same, held my weight. (More of a hassle to take though, and tastes horribly, so on the whole I vastly prefer the Ozempic.)

Then, earlier this spring, that prescription ran out. Being in the middle of changing my primary healthcare provider I couldn't immediately get it renewed. And to be honest I wasn't at first all that bothered; I thought now that I've lost so much weight, and kept it off for so long with the help of these drugs, maybe I've got into the habit of eating less, so I can stay constant without them? Nope – in just a few weeks, ballooned back up some 8-10 kg. Had to scramble a bit to get the pill prescription renewed, been on it again for a couple weeks, but still some 6-7 kg above where I was before they ran out. Sure hope I'll get back down the rest of the way.

TLDR: Anecdata (n=1) says yes, going off the drugs even for a rather short while puts the weight back on quite quickly.