print(f"{person}:") SyntaxError: invalid syntax when running it

[Axel_Erfurt]

python heredityarya.py data.csv starts the script with python2 which has no f-strings

[snippsat]

Ok. But already have Python 3.8.3 downloaded from python.org. And the problem/issue remains the same.

Use Homebrew to mange install and alias to Python 3 on Mac,as you use.
The right and wrong way to set Python 3 as default on a Mac
Under Have Homebrew manage Python 3.

There also in the post a some about pyenv brew install pyenv
Look also at this pyenv Simple Python Version Management
wiki for Mac.