Get len from string containing extended ASCII characters

[r0n]

Sorry for this stupid question but below I have 7 characters in _s from the extended ASCII table found in [ALT]+196
But _s.len gives an incorrect value. I always used this to get the amount of characters but maybe I used incorrect method?

_s="───────" ;; Extended ASCII character ---> https://www.asciitable.com/ --> ALT 196

_s.len does not return 7, it returns 21