Feels like a font issue. Do you have e.g. nerdfont installed and in use in your terminal? You could check the config for plugins that makes that style, and check which fonts are in use. Could also be powerline fonts that are needed: https://github.com/powerline/fonts

For me, Andreas Kling and his work on the SerenityOS and Ladybird browser is enjoyable to watch. I recommend watching the JIT-series, Jakt-series (his and JT's programming language they created). Actually all the series on the channel are great 😄 Also JT's videos on Nushell and his series on the NES-emulator written with Jakt are good.

https://www.youtube.com/@awesomekling
https://www.youtube.com/@SystemsWithJT

Vikunja is one option. Selfhosted, open source and Trello-like.