Font showing strange characters in konsole (Kubuntu 20.04)

Assuming you ran ls -l to show that image, looks like the Month for the modified date is not showing correctly. Some things to try:

• Check that Language and region system settings is correct and the language settings.
• Run echo $LANG to see what the console language is and that it matches the system setting, and that the language is currently installed on the system. You may need to find out what packages you need and install them sudo apt install {language packages}
• Check that your font setting is correct and supports your chosen language
• You mentioned you already tried a few fonts. I use Hack font or FiraCode which supports a lot of different symbols, you could try those if
• For some commands you can enter LANG={language-code} {command} to force it in a particular language (The language should be installed on your system first). For example: LANG=fr_FR ls -l or LANG=en_GB ls -l