Like, how?

Running it a few times and not seeing any errors doesn't prove you don't have a race condition!

I had a race condition that appeared in a C++ project twenty years ago that I finally tracked down. It happened on average once every 44,000 times it went through a certain point, but when it did, it caused a crash. (And never in debug mode. I only finally figured it out by carefully reading all the code, it was a slog.)

There are no plans at all for the main Python executable, the one that you download by default, to have the GIL removed. Everyone's best guess is that it would make almost every multithreaded Python program unreliable.