Simpler reproducer:

>>> f"{foo)"
  File "<stdin>", line 1
    f"{foo)"
            ^
SyntaxError: f-string: unmatched ')'

I assume this is the same error as:

>>> foo)
  File "<stdin>", line 1
    foo)
       ^
SyntaxError: unmatched ')'

But I don't yet understand why it's choosing to parse that expression fragment. I'm working on it.