I came across this older article from 2020 and I found it informative. It's about how the shell does globbing and the potential issues it can cause if not understood correctly.

TLDR:

find . -not -name *.py -delete and find . -not -name '*.py' -delete will behave differently in certain scenarios.

In the first example, the shell will replace the wildcard pattern with a list of matching file names IF there are any matches in the current directory. If there isn't, then it won't do anything and will pass *.py to find.

In the second example, the shell won't do any globbing at all and will just pass *.py