There’s a line between being useful and being used. Usually it’s a thank-you.

Helping people feels good right until it quietly becomes assumed. The tell is small and easy to miss: nobody thanks you anymore, nobody asks whether you have time, the task simply lands on you because it always has. That shift is rarely anybody being cruel. People adjust to whatever you keep doing for them.

Think about what you have been handling lately and whether anyone has acknowledged it in the last month. If not, treat that as information rather than a grudge. Try saying you can do it this once but not every week, and see whether the thanks comes back.