After sterilizing, male cats will still be in estrus, but will not have children. Even in estrus, the male cat will not have any fertility behavior because its reproductive system has been spayed.
The male cat still has estrus after sterilization. It may be because the hormones in the body have not yet faded. When the cat has this time, the hormones will gradually fade and will no longer feel estrus.
If the owner is very worried about the cat's estrus, you can use a banned fan for the cat, and just get through this estrus. The sterilization of the male cat was not done cleanly, and it was possible that the doctor only picked one egg, so he needed to go to the hospital for examination.