a stipend does not rise to the level of being a trade or business there is no profit motive. you're also using a code section, 1202, which is used to define a specified service trade or business which has special rules for the QBI deduction.
if the institution deemed you to be engaged in a trade or business it should have issued you a 1099-NEC. then the amount would have been subjecst to about 15% in self-employment taxes.
