I get an unexpected error when attempting to sign in to Firefox on my Windows 11 laptop when already signed in on a Windows 10 laptop and iphone.

I used to be synced across two laptops and my iphone but no longer. I am signed in to my Firefox account on my Windows 10 laptop and on my iphone. The windows 10 laptop indicates that I am also signed in on my Windows 11 laptop, but when I run Firefox on my Windows 11 laptop, it indicates that I am signed out. When I attempt to sign in (on the Windows 11 machine), I get an "unexpected error" flag and I cannot sign in.

How can I fix this?