R 绘图仪中的水平虚线

我试图在plotly制作的气泡图中绘制虚线，但在执行代码时发生了一些奇怪的事情。虚线出现了，但在虚线的两端画了两个大气泡，我不明白为什么会这样。代码如下：

iris2 <- iris
binary_variable <- factor(sample(x = c(0, 1), size = nrow(iris2), replace = TRUE))
iris2 <- cbind(iris2, binary_variable)

m <- glm(binary_variable ~ Sepal.Length + Sepal.Width*Species, family = binomial, data = iris2)

plot_ly(x = ~hatvalues(m), y = ~rstudent(m), type = "scatter",
  mode="markers", colors=~colors, size=~cooks.distance(m),
  marker = list(symbol = 'circle', sizemode = 'diameter',
                line = list(width = 2, color = '#FFFFFF'), opacity=0.4),
  text = names(rstudent(m)),hoverinfo = 'text') %>% 
  layout(title = "Gràfic d'influència", xaxis = list(title = "Hat Values"), yaxis = list(title = "Studentized Residuals")) %>%
  add_segments(x=min(hatvalues(m)), y=2, xend=max(hatvalues(m)), yend=2, line=list(color="red", width = 1, dash = 'dash'))

iris2