When not to use f-strings?

[snippsat]

I use only f-string for string formatting now,and have done so for a while(years).
They are more readable,more concise,and less prone to error than other ways of formatting,they are also faster!.

For me is very simple to see this.

>>> name = "Kent"
>>> age = 30
# The  expressions is in the string where the belong
>>> print(f"Hello, {name}. You are {age}.")
Hello, Kent. You are 30.

# The  expressions is behind and not where the should be,and only {} in string
>>> print("Hello, {}. You are {}.".format(name, age))
Hello, Kent. You are 30.

2) Is it something with f-strings and newlines to be timed? (no problems to print)

Don't pack in a string,use a function.
There is no need to measure,they are faster.

import timeit

def run_me():
    newline = '\n'
    first = 'first'
    second = 'second'
    "\n\nThis is printing strings with f-formatting:"
    f'{first}{newline}{second}'
    #'{}{}{}'.format(first, newline, second)

print(timeit.Timer("run_me()",'from __main__ import run_me').timeit(number=10000000))

Output:
f-string: 3.2901052
.format(): 6.3253624