Run screen in UTF-8 mode. This option tells screen that your terminal sends and understands UTF-8 encoded characters. It also sets the default encoding for new windows to ‘utf8’.”
(none)
Same as the ‘utf8’ command except that the default setting for new windows is changed. Initial setting is on if screen was started with ‘-U’, otherwise off.”
This can lead to ghost characters that aren't shown, overlapping characters, etc.
It was an attempt to bolt on UTF8 support, but it's not great.