Post-Fire Flooding and Debris Flow Act of 2022 This bill makes changes to eligibility under the hazard mitigation grant program of the Federal Emergency Management Agency (FEMA) to include mitigating and preventing post-wildfire flooding and debris flow. Specifically, the bill requires the federal share of hazard mitigation assistance for mitigating and preventing post-wildfire flooding and debris flow to be not less than 75% of the cost (currently, the President may contribute up to 75% of the cost).