The best place to get information is on your state's unemployment website since there may be variance in how different states are impacted.
This is what the Dept. of Economic Security in AZ says:
The impact to your benefits depends on the circumstances of your claim. To determine the impact on your claim, please see the description below that best describes your unemployment situation:
New applicants for unemployment – If Congress does not extend the Federal Additional Compensation (FAC) program, and you apply for unemployment after February 28, 2010, you will not be eligible for the additional $25 per week payment provided through the FAC program. If Congress approves an extension to the FAC payment in the future, you may be eligible for a $25 retroactive payment for each week you receive benefits.
If you currently receive regular unemployment - You can continue to receive regular UI benefits (including the $25 Federal Additional Compensation payment) until you exhaust all your regular benefits. If Congress approves an extension of Emergency Unemployment Compensation (EUC) or Extended Benefits, you may be eligible for additional payments beyond the termination of regular unemployment.
If you currently receive Emergency Unemployment Compensation (EUC), Tier 1 through Tier 4 – You will not be eligible for the all the benefits under EUC unless Congress votes to continue the program. However, you can continue to receive EUC benefits (including the $25 Federal Additional Compensation payment) thru the end of the EUC tier you currently receive. If Congress approves an extension in the future, you may become eligible again for the remaining tiers of EUC. It is very important that you continue to file weekly claims. This could allow you to obtain retroactive benefits on a more timely basis if Congress continues the EUC program.
If you currently receive Extended Benefits (EB) – Your eligibility for unemployment benefits will end during the week of March 6, 2010, unless Congress approves an extension of the EB program. However, you may become eligible again if Congress approves an extension and you may be able to receive the balance of your claim. For this reason we urge you to continue to file your weekly claims for weeks ending after March 6. The Department will place all EB claims for weeks after March 6 on hold. If funding is restored the Department will notify you and release payments. If you stop filing weekly claims, you will need to call the UI Call Center to reopen your claim.
https://www.azdes.gov/main.aspx?menu=317&id=5196