How to trigger the bug

1. Take damage
2. Eat a meal
3. ???
4. Profit

Why it does this:

1. The game keeps track of time using an internal counter called hungerCounter. This counter gets increased every time the game ticks in the OnGameTick method of the EntityBehaviorHunger class. Because the game tick speed is not an exact number it just accumulates by about one second.
2. Once the hungerCounter exceeds 10, it is assumed that 10s of real world time have passed.
3. The OnGameTick method of the EntityBehaviorHunger class triggers a ReduceSaturation method.
4. This method checks to see if there is any meal delay (because of the benefit of eating meals as you pointed out).
5. If there is still a delay, the delay has a small number subtracted from it and a variable is set called isondelay and given a true/false value of true.
6. If isondelay is set to true, the game will then subtract 10 from the hungerCounter and the method ends.
7. IF the player is injured, the game will attempt to exchange satiety for health. It does this by calculating an amount of satiety to consume every game in the OnGameTick method of the EntityBehaviorHealth class. NOTE: This is different from the previous EntityBehaviorHunger class. It then sends this value to a method called ConsumeSaturation.
8. ConsumeSaturation does not adhere to the 10s rule because it is outside of the OnGameTick method of the EntityBehaviorHunger class. Thus instead of being called once every 10s, it is being called once every 1s. It gets called 10x as often when the player is injured!
9. ConsumeSaturation does some calculations and passes the value off to ReduceSaturation! Remember this is once every 1s instead of once every 10s!
10. Because the player JUST ate, the meal delay values are quite high. Because you are only sacrificing a small amount of hunger to regenerate your health, the meal delay values take a long time to decrease. Every time this happens, the hungerCounter is lowered by 10.

So to summarize:

1. The game increases hungerCounter by roughly 1s every game tick.
2. If the player is injured and has a meal delay, hungerCounter is decreased by 10s every game tick. This has a net result of lowering hungerCounter by roughly 9s every game tick.
3. If it takes a couple of minutes for the player to heal, hungerCounter will decrease to -1080 or so, meaning it's going to take another 1090 or so ticks for the hungerCounter to reach 10 again.
4. 1090 ticks is 18 MINUTES of real world time. A day in Vintage Story takes 48 minutes of real world time. By doing some math, that's 9 in-game hours of the satiety meter not budging because hungerCounter never gets over 10 and thereby never triggers ReduceSaturation again.

This is a real problem, and that is what this mod is addressing.