Primeiro, verifique se a variável de configuração ZLE_RPROMPT_INDENT
to 0
ajuda. O padrão é 1
.
Do manual do zsh:
ZLE_RPROMPT_INDENT
If set, used to give the indentation between the right hand side of the right prompt in the line editor as given by RPS1 or RPROMPT and the right hand side of the screen. If not set, the value 1 is used.