The IRS refunded my excess APTC payment that I paid on my 2020 Form 8962. Am I now required to amend my California State tax return to reflect the refund when technically I did not amended my Federal return?
No, the IRS says you don't need to Amend due to a refund for Advanced Premium Tax Credit.
"Individuals in this situation should not file an amended tax return to get a refund of this amount. The IRS is taking steps to reimburse taxpayers who filed Form 8962, reported, and paid an excess advance Premium Tax Credit repayment amount with their 2020 tax return."
Since this affected your Federal Refund, it most likely doesn't affect your California return.
However, if you wanted to check, save a copy of your originally filed returns. Open your 2020 Federal return to Amend, which should show no APTC is due (after updates). Then Continue to Amend your California return to see if your refund changed. If not, no harm done.
If it does change your California refund, you could go ahead and file an Amended Return.
Click this link for more info on How to Amend a Prior Year State Return.