ACKTUALLY, whether or not you can get fired is a state issue, and some states such as California provide statutory protection for employees who use cannabis. It’s true that there are some states where you can get in trouble, but the federal laws are not being enforced by the Biden administration, who has given the green light on cannabis consumption and rescheduling, so there’s really no single answer that applies to the whole United States, and your mileage may vary.