Twitter's definition of state-affiliated:

How state-affiliated media accounts are defined

State-affiliated media is defined as outlets where the state exercises control over editorial content through financial resources, direct or indirect political pressures, and/or control over production and distribution. Accounts belonging to state-affiliated media entities, their editors-in-chief, and/or their prominent staff may be labeled. We will also add labels to posts that share links to state-affiliated media websites.

Conspiracy theories aside, AFAIK there's no evidence that any level of the US government exercises control over NPR.