Yes, you've encountered a bug. It's got these two tickets:
https://rt.perl.org/Public/Bug/Display.html?id=124898
https://rt.perl.org/Public/Bug/Display.html?id=131964
I've got a branch in nqp and rakudo that I'll merge very soon that fixes
both of these bugs.
Until then you can switch $ and ^,
I want to match something anywhere but at the end of a string in one
example, or anywhere but at the start of a string in another example. The
"except at start" one has me stumped. Not sure if it's me or if I've
tickled a bug.
perl6 --version
This is Rakudo Star version 2018.01 built on MoarVM