Bash command to generate random password breaking on macOS Big Sur upgrade

I used the following bash command to generate a random password of length 5 previously on macOS Catalina. When I updated to macOS Big Sur, this now displays random non-unicode characters.

export LC_CTYPE=C && head /dev/urandom | tr -dc a-z0-9 | head -c5
e1q�y

Any idea what needs to be modified?