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I set icons:

typeset -g POWERLEVEL9K_MULTILINE_FIRST_PROMPT_PREFIX="%{%F{050}%}\u250f"
typeset -g POWERLEVEL9K_MULTILINE_LAST_PROMPT_PREFIX="%{%F{050}%}\u2517%F{cyan}\uF460%F{073}\uF460%F{109}\uF460%f "
I want to set the same icons for RIGHT side too! How can I rotate these icons?
...source Modified Abyss for VSCode.
Replace your two lines with this:
typeset -g POWERLEVEL9K_MULTILINE_FIRST_PROMPT_PREFIX='%F{50}\u250F%f'
typeset -g POWERLEVEL9K_MULTILINE_FIRST_PROMPT_SUFFIX='%F{50}\u2513%f'
typeset -g POWERLEVEL9K_MULTILINE_LAST_PROMPT_PREFIX='%F{50}\u2517%F{6}\uF460%F{73}\uF460%F{109}\uF460%f'
typeset -g POWERLEVEL9K_MULTILINE_LAST_PROMPT_SUFFIX='%F{109}\uF47D%F{73}\uF47D%F{6}\uF47D%F{50}\u251B%f'
Most helpful comment
Replace your two lines with this: