Can you tell me why there is a separate banner for Russian localization?
app/views/custom_styles/_inline_css_logo.erb

<style type="text/css">

  <%

  isRu = I18n.locale == :ru

  logo_url = if isRu

               asset_path("logo-white-bg-ua.png")

             else

               asset_path("logo_openproject_white_big.png")

             end

  high_contrast_logo_url = if isRu

                             asset_path("logo-black-bg-ua.png")

                           else

                             asset_path("logo_openproject.png")

                           end

  high_contrast_bim_logo_url = asset_path("bim/logo_openproject_bim_big_coloured.png")

  if apply_custom_styles?

    if CustomStyle.current.logo.present?

      logo_url = custom_style_logo_path(digest: CustomStyle.current.digest, filename: CustomStyle.current.logo_identifier)

    elsif CustomStyle.current.theme_logo.present?

      logo_url = asset_path(CustomStyle.current.theme_logo)

    end

        if isRu && logo_url == asset_path("logo_openproject.png")

      logo_url = asset_path("logo-black-bg-ua.png")

    end

  end

  %>