Interesting. I remember using
https://www.grc.com/passwords.htm as a source for some random stuff long ago, but I would take some from one string, then reload the page a few times and grab some more characters, building a random string with pieces from several of the provided ones just in case that wasn't as secure as they claimed. That process probably didn't really help.
These days I just use `apg`: https://linux.die.net/man/1/apg