There may be many reasons for a cat to suddenly pee on the bed. Here are some common possibilities:

1. Cat litter box problem: The litter box may be unclean, or the cat may not like the litter. The texture, the smell, they may choose other places to excrete.

2. Health problems: Some cats may also show unusual behaviors when they feel physical discomfort or pain, and then choose to pee on the bed or other places.

3. Behavioral habits: Some cats may pee on the bed out of habit or curiosity.

4. Stress or anxiety: Changes in the environment, new family members, the presence of other pets, or other stressors may cause Cats become anxious and exhibit unusual behaviors, including peeing on the bed.

5. Marking territory: Cats sometimes mark their territory by peeing. This usually occurs in a multi-cat household or when a new cat joins the household, and is a behavior the cat adopts to assert its sovereignty.