FAST Fix Act of 2021 This bill modifies provisions governing the administration of the Federal and State Technology Partnership (FAST) program. Specifically, the bill encourages FAST program grants to be awarded to small businesses in underperforming states by requiring the Small Business Administration (SBA) to prioritize such applicants and authorizing the SBA to provide additional assistance to such applicants. The bill defines underperforming states as being the 18 states that receive the fewest Small Business Innovation Research and Small Business Technology Transfer awards. Additionally, the bill removes the limit on the number of proposals that may be submitted for inclusion in the FAST program to provide services in any one state. The bill also lowers the matching requirements for the bottom tier of FAST recipients, sets limits on the amount of each award, and extends the period for distribution of grants to two years.