I suspect a lot of the controversial decusions made doing the 2to3 migration by the python foundation was deliberately designed to avoid a situation similar to what happened to perl when the time came to cleanup some of the old cruft from the language.
It was a necessary change too. Supporting Unicode strings or mixed-encoded strings was absolutely awful in Python 2 and almost not worth doing. Python 3 made that work properly.
Arguably, the only real mistake was using UTF-16 instead of UTF-8 for strings. But back then, nobody knew what would take off and Windows natively uses UTF-16, so...
Raku is a completely different language from Perl. Writing Raku instead of Perl 5 is like writing Rust instead of C++.