@MontgomeryGator @mawr Haha nice!

Turns out the secret sauce is adding 0x000e0000. So this should work to decode:

󠁡󠁷󠁯󠁯󠀠perl -CS -pe '@_ = split(//); $_ = join "", map { chr(ord($_) & ~0x000e0000) } @_;'

And this to encode:

perl -CS -pe '@_ = split(//); $_ = join "", map { chr(ord($_) | 0x000e0000) } @_;'

Emoji don't work right, since they live up in that range too. Maybe the solution is to add/subtract 0x000e0000 instead of bitwise set/clearing it.