Perhaps the reason is prevention of food poisoning.
Images are from Scripture4all.org - Interlinear ISA-2 program.

Strong's H6292 pigguwl pig-gool'
or piggul {pig-gool'};
from an unused root meaning to stink; properly, fetid, i.e. (figuratively) unclean (ceremonially).
KJV: abominable(-tion, thing).

The same explanation is given here, except with more detail. Seems the last part of the verse might make more sense, "depravity-of~her you~shall-bear."
As for burning leftovers after one day:
Exo. 12:10 - And ye shall let nothing(3808) of(4480) it remain(3498) until(5704) the morning;(1242) and that which
remaineth(3498) of(4480) it until(5704) the morning(1242) ye shall
burn(8313) with fire.(784)
Exo. 12:11 - And thus(3602) shall ye eat(398) it; your loins(4975) girded,(2296) your shoes(5275) on your feet,(7272) and
your staff(4731) in your hand;(3027) and ye shall eat(398) it in
haste:(2649) it(1931) the LORD's(3068) passover.(6453)
They had to be ready to head out of Egypt on a moment's notice, so holy food was to be disposed of properly.
I've read in several places where the Hebrews were the first to establish hygiene practices (physical and spiritual) to prevent disease - God taught them. (And it isn't as if they had refrigeration.)
Not saying that there couldn't be more to the story, but I simply don't feel 'the pull' to look further than the simplest explanation in this case. Maybe someone else will find something deeper.
Note: I do find it interesting that it is 'her depravity' that causes the food to spoil.... For that juicy morsel, I thank you for the question.