I did a Find on AB 80 and found relative reference to CARES and CAA; not to March. This article:

https://www.ftb.ca.gov/about-ftb/newsroom/covid-19/paycheck-protection-program-loan-forgiveness.html

Has:

"The Paycheck Protection Program Extension Act (PPPEA) (Public Law 117-6) was enacted on March 30, 2021, and extended the covered period of the PPP from March 31, 2021, through June 30, 2021. California law does not conform to this extension and does not allow an exclusion from income for PPP loans made after March 31, 2021."