I'm somewhat of a newb when it comes to all this and wasn't sure if I should/how to properly submit this as a bug, but I thought I would share anyway in case it help someone.

When performing a new install of Ubuntu 20.04, I changed the keyboard region from US to UK. Then I created a username and password, only to find I kept getting told the password was incorrect. After much searching for a solution I couldn't find one, so did a fresh install again, and decided to write the password in the name field and then copy and paste it over.
This is when I found that some of the special characters I was using in the password were not the ones I had typed. For example, in further tests, the @ character had been changed to ".

Again, I haven't come across this issue elsewhere, so I thought I'd share it here.