There are many possible reasons why a cat may not like having its tail stroked at night. One reason is that your cat may feel somewhat uncomfortable or uneasy having its tail touched, especially if it is sleeping or resting. Another reason is that a cat's tail is an important tool for expressing emotions and communicating, so if you touch its tail, it may feel disturbed. Another reason is that your cat's tail can be a sensitive area for her, especially when she's on alert. If you suddenly touch its tail, it may perceive this as a threat and respond with a wary or aggressive response.
In general, if you want to have close contact with a cat, it is best to observe its reaction first and then try Gently touch its head or chest to see if it is willing. If he likes it, try stroking his tail gently. Remember, cats are independent animals with their own preferences and wishes, so respect their wishes.