Fricking crazy- I had no idea. All of it and it's not just me - others find exactly the same. There's a newer daily stress line chart that shows where you are and have been for a number of preceding hours. During quality sleep it's low and largely flat. If I eat a decent sized meal (even super healthy) it bounces around moderate and only gets low and flat in the final period of sleep. This also correlates to resting heart rate, heart rate variability and other factors that influence your overall recovery metric. Digesting a meal of substance takes energy/effort I guess and it impacts your sleep.
Lots of other people noticed it too. Now late night drinking is also similar and even worse so it's a spectrum. If going for optimal, I'd avoid food 3hrs before sleep or more. Others found the same. Can probably sneak in a small snack or a protein shake but it's real. It makes sense but I didn't realize the magnitude of work/effort going on as it's subconscious.