It takes about 24 hours to hit peak blood levels after a dose, so minimum blood levels would be just before the next dose, and rising after that to a peak 24h later or so. Immediately after the dose levels will be low but should be rising.
If it was due to the drug wearing off it should be worse before the next dose not after, and if it was nausea as a side effect, it should be worse 24 hours after the dose.
My guess and it is a guess, is maybe it is a bit of low grade nausea, as the blood levels are rising, it can be really hard to tell the difference between that and hunger sometimes. I had a year of nausea and hunger on low dose ozempic, which I was using to try to reduce being permanently starving after losing 70kg without glps. And I found I was often both hungry and nauseous, or could not tell which was which, or had nausea that I could fix by eating a tiny bit of chocolate or sugared ginger.
It is not hard to try splitting doses to see if it works.