However, the subject said that the leader "likes" to let you do it. I think you gave everything you wanted before. He thinks you are a useful subordinate and is used to calling you. Another situation is that you have done a good job in extra work, and the leaders are very satisfied with you and think you are reliable, so no matter what happens, they will think of you.
My suggestion is that if this extra job doesn't contain much gold, it can be done by someone at a lower level, and you can refuse it. Because there is no need to spend high prices to make people do low-value things, the cost performance is too low.
If you have done too much in the past, please learn to "refuse" now, and you must be well-founded and have a high emotional intelligence, so that leaders can feel that your current job is the most important, and you can rest assured that foreign affairs are handed over to others.
Sometimes people will hesitate because of the interests, fearing that the superior officials will crush you to death, and fearing that the current refusal will affect your future career life. However, please think about it from another angle. If you don't refuse, it will still bother you. When the work is saturated, you have to do extra things. Do it well, do it badly, and you are responsible for the risk.
If things themselves can exercise you well, that's another matter. However, it's best not to give outsiders anything that you exceed your authority, otherwise there will always be people in the workplace who like to gossip, and the story of three people becoming tigers is not without it.
If you are in the human resources department, other departments sort out the process system and so on, although it doesn't belong to you, you can go if the leader wants your help. First of all, this job has something to do with your own job. Secondly, when you assist, you can be more aware of the workflow of other departments, so as to know more about the company, which is more conducive to your later work and skills improvement.