Falcon is correct. I served as a 'Ditch Pig' in November 2016, cleaning the Camino in Palencia for a week.
TP or other type tissue, seen away from a tree line or hedgerow is typically 'nose-blow' detritus. The really nasty stuff, or "brown tissue' as we came to refer to it, is usually in a sodden pile or wad, behind something that may have provided some privacy during the spring and summer months.
Once otono / fall / autumn arrives, and leaves drop from trees, the spotty white patches become all the more apparent. The curtain is parted and the sins of the pilgrim are revealed...
If you carried it into that location, you should pack it out after use. If that is not doable for any number of reasons, do carry a lightweight 'cat sanitation' trowel, and bury your soiled 'stuff' in a small hole, well covered over before you depart.
The very few times this has occurred to me over six Caminos, I went the added step of burning the paper over the 'stuff' using the small BIC lighter I always carry in my belt pocket. this speeds decomposition, reduces attracting wildlife, and reduces the overall size of 'the deposits.' Of course, I had one or more water bottles ready to immediately douse any flame that threatened to spread. After the fire is well out, I filled in the hole, compressed it with my boot, and covered the area with vegetation.
So, the best advice, IMHO, on this issue is:
- plan your toilet needs ahead of time, tend to them in a proper place...a bathroom / bano / loo, etc.
- pack out whatever 'trash' you create, from any source. Leave only memories...
- properly dispose of and minimize whatever detritus you must leave behind.
- THINK of others who come after you.
Hope this helps.