For DHS, the production year and season are imprinted on the paper packaging. The two numbers mean the year and the letter, either A, B, C or D mean the season. A is January to March, and so on.
The printing on the sponge is code.
X-0 A-1 B-2 C-3 D-4 and so on. Translate it and you will find that only four(commercial) or six( provincial) of the numbers(all next to one another) can be read as a valid date(ie.202201 for provincial and 2201 for commercial). Match this date with the one on the packaging.