There are several possible reasons why your cat pees on the bed. Here are some of them:

1. Medical problems
Urinary tract infections: Cats can develop urinary tract infections or infections, which can cause them to feel the need to urinate more frequently.
Kidney problems: Kidney diseases can cause the cat to drink more and urinate more, and sometimes it may not reach the litter box in time.
Other physical problems: You should contact a veterinarian to check if there is a medical problem.
2. Stress or anxiety
Changes in the environment: changes in the home such as moving house, the arrival of a new person, or a new pet can make the cat feel uncomfortable.
Loud noises: external noises such as thunder or gunshots may make the cat feel anxious.

3. Behavioral problems
Territory defense: Cats sometimes urinate to mark their territory. If another cat comes into the house or if there is any change, it can cause him to act like this.
Improper training: If the cat is not properly trained to use the litter box, it may look for other places to urinate.
4. Preference for a certain place
Comfort: Cats may prefer to urinate in soft or warm places like beds.
Odors: If your bed smells like cats or other animals, he may think it's a good place to pee.

what to do
Medical examination: If this behavior is new or sudden, the cat should be examined by a veterinarian.
Improving the environment: the cat certainly feels safe at home. You can create quiet and pleasant areas for him.
Instructions in the litter box: Make sure the box is clean, accessible and in a quiet place.
Re-education: If it is a behavioral problem, you may need to re-educate the cat and use positive methods to encourage it to use the litter box.
If the problem persists, you should contact a veterinarian or a cat behaviorist for further advice.