Your manager is supposed to manage you. In your situation, your manager is not managing. My rule in situations like that is: I only do work that comes from my

Your manager is supposed to manage you. In your situation, your manager is not managing. My rule in situations like that is: I only do work that comes from my manager, or trusted people that my manager has directed me to work with. All other requests for work (that don't come through my manager or people who I am actively working with) are either: responded to with a polite 5-15 minute conversation where I give information / advice and make no commitments; directed to my manager; re-assigned back to the person who assigned them to me; ignored; or I will say no. (IE, if you use a system like Asana, and someone you don't have a working relationship with assigns a task to you, just re-assign it back to them. Then, depending on context, either offer to have a short Q&A or suggest that they seek out your manager to determine who should complete the task.)