Getting strange character output in PuTTY on one Ubuntu machine

[Colin Law]

On Wed, 28 Jul 2021, 07:10 Bo Berglund, <bo.berglund at gmail.com> wrote:
>
> I am probably missing something simple but I don't know what...
>
> I have multiple Linux machines (like 10+) including PC:s using Ubuntu 18 and 20
> or Raspberry Pi:s using Pi-OS.
> I access all of these using PuTTY from my Windows PC and all behave sensibly
> except for one Ubuntu 20.04.2 LTS PC on which the PuTTY output always is using
> strange characters instead of normal ones:
> For example when using "sudo apt update" I should get this as the final result:
>
> Fetched 3 675 kB in 1s (2 804 kB/s)
>
> But instead the space in the two numbers 3 675 and 2 804 is replaced by a square
> box!

What does
cat /etc/default/locale
show in a good system and the bad one?

Colin L.