[AlexSW]

I personally have run into breaking changes in Python's regex module, which is pretty fundamental to such uses as mentioned above.

If I recall correctly, they changed how `re.escape` worked between Python 3.6 and 3.8 (I'm not sure which minor change exactly) in terms of which symbols received a backslash before them, thereby breaking my code.

[formerly_proven]

Perl 5 had a change there, too, in between the versions shipped in RHEL 7 and 8, iirc something about {} changed.