Has your cat suddenly started pooping on the carpet, ignoring the perfectly clean litter box?
Before you get angry, check - maybe the problem is in you. Cats are extremely sensitive to small things.
For example, if the tray is next to a washing machine that hums when spinning, your pet will avoid it. Or you bought a new filler with a "lavender scent", and the cat cannot stand strong smells.

Another reason is competition. If there are several cats in the house, they may not have enough litter boxes. The rule is simple: number of toilets = number of cats + 1. Put them in different rooms, and conflicts will disappear.
But there are also strange cases. For example, the cat started marking the door after you brought a new bag from the store. He senses someone else's smell and tries to cover it with his own.
To avoid this, wipe things with a damp cloth before bringing them into the house. And if the cat stubbornly defecates in one place, block its access there. Put a bowl of food - cats do not go to the toilet where they eat.
The most radical method is re-education. Put the cat in a room with a litter box for 2-3 days. Every time he goes correctly, praise him and give him a treat.
If he makes a mistake, remove it without emotion. In a week, the habit will become ingrained.