Is it normal that running python under valgrind shows many errors with memory?
You could try using the suppression file that comes with the python source
Reading the Python Valgrind README is a good idea too!
This is quite common, in any largish system. You can use Valgrind's suppression system to explicitly suppress warnings that you're not interested in.
Following links given by Nick I was able to find some updates on README.valgrind. In one word, for Python > 3.6, you can set PYTHONMALLOC=malloc environment variable to effectively disable the warnings. For example, in my machine:
export PYTHONMALLOC=mallocvalgrind python my_script.pydoesn't produce any error related to python.