Cygwin is nice, but it's a Frankenstein's monster. I'd hold back critical thoughts and feelings, until testing elsewhere.

You'll be happiest.

yeah it sounds like your environment is doing some weird mangling of the encoding. Maybe consider adding an 'alias man="man -E ascii"' into your .bashrc

You might also consider seeing if it's any different in WSL. Or you could, you know, just use Linux ;P