Fish-shell: Can't see "simple pythonista"-prompt when ssh to remote machine 👻

[TGotwig]

The simple pythonista-prompt doesn't show up when I ssh into a remote machine,
but I can run commands like echo:

tgotwig at Thomass-Air in ~
↪ ssh [email protected]
[email protected]'s password:
Welcome to Ubuntu 20.04 LTS (GNU/Linux 5.4.0-37-generic x86_64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage


0 updates can be installed immediately.
0 of these updates are security updates.

Your Hardware Enablement Stack (HWE) is supported until April 2025.
Last login: Thu Jun 18 11:09:43 2020 from 217.230.46.5
Hi Tux! 🐧
Welcome to fish, the friendly interactive shell
Type `help` for instructions on how to use fish
echo 123
123

Others like Minimalist works fine:

tgotwig at Thomass-Air in ~
↪ ssh [email protected]
[email protected]'s password:
Welcome to Ubuntu 20.04 LTS (GNU/Linux 5.4.0-37-generic x86_64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage


0 updates can be installed immediately.
0 of these updates are security updates.

Your Hardware Enablement Stack (HWE) is supported until April 2025.
Last login: Thu Jun 18 11:18:19 2020 from 217.230.46.5
Hi Tux! 🐧
Welcome to fish, the friendly interactive shell
Type `help` for instructions on how to use fish
tgotwig ) echo 123
123
tgotwig )

I'm using iTerm2 for connecting from MacOS to Ubuntu 20,
this issue also shows up with the default terminal on MacOS,
further informations from the remote machine:

tgotwig ) fish --version
fish, version 3.1.0

tgotwig ) uname -a
Linux tgotwig-MS-7B84 5.4.0-37-generic #41-Ubuntu SMP Wed Jun 3 18:57:02 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

tgotwig ) echo $TERM
xterm-256color

tgotwig at Thomass-Air in ~
↪ ssh [email protected]
[email protected]'s password:
Welcome to Ubuntu 20.04 LTS (GNU/Linux 5.4.0-37-generic x86_64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage


0 updates can be installed immediately.
0 of these updates are security updates.

Your Hardware Enablement Stack (HWE) is supported until April 2025.
Last login: Thu Jun 18 11:19:10 2020 from 217.230.46.5
Hi Tux! 🐧
Welcome to fish, the friendly interactive shell
sh -c 'env HOME=$(mktemp -d) fish'
Welcome to fish, the friendly interactive shell
Type `help` for instructions on how to use fish
tgotwig@tgotwig-MS-7B84 /h/tgotwig> echo 123
123
tgotwig@tgotwig-MS-7B84 /h/tgotwig>

[faho]

Please update fish to 3.1.2 and/or set your locale to something unicode-capable. Ideally both.

This is #6736.