Loose fibres from one textile can show strongly on another, making a completed load look dirty despite the original washing result. Contrast and shedding are relevant sorting factors.
Understanding this situation
This is different from colour dye transfer or detergent residue. Identifying the material helps avoid treating a physical fibre issue with unnecessary chemicals or assuming the dryer creates stains.
A useful next step
Use compatible loads and routine filter care. Remove loose fibres from garments only by an appropriate method. If deposits persist unusually or include hard, oily or melted material, report that distinction instead of treating every mark as ordinary fluff.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.