It is earned income, but not self-employment. To enter your strike pay on a 1099-NEC, you will need to mark the box that says, This is not money earned as an employee or self-employed individual. It is sporadic or hobby income (this is rare). They should have used form 1099-misc, and you may want to request a corrected version (the IRS assumes income on 1099-nec is self-employment).
**Say "Thanks" by clicking the thumb icon in a post**Mark the post that answers your question by clicking on "Mark as Best Answer"