It's an indexing error
Try like this:

    // Create new entry label
    long_entry_label := label.new(
      bar_index, low, 
      text="LONG ENTRY\nLeverage: " + str.tostring(leverage_long) + "x\nPrice: " + str.tostring(close, format.mintick), 
      color=bgcolor_with_transparency(long_entry_color), 
      style=label.style_label_up, 
      textcolor=label_text_color, 
      size=label_text_size,
      yloc=yloc.belowbar)