I moved after filing an amended return. I've activated USPS mail forwarding. Will USPS forward my refund check?

Timeline -

03/26/2021 - IRS received my amended return.

06/29/2021 - I moved to a different location and activated USPS mail forwarding. IRS is still processing my amended return.

 

If I get a refund check addressed to my old address, will USPS forward it to my new address? Or does USPS have any rules that forbid them from forwarding IRS checks? What will happen in my case?

 

Do I need to fill up form 8822 to notify IRS of my change of address? Or does the USPS mail forwarding suffice?