why is it showing wrong date format in dygraph

why is it showing wrong date format and I tried to aggregate the data but it did not work.

aggregate(. ~date,data=data,fun=sum)

library(shiny)
library(plotly)
library(dygraphs)
library(forecast)
library(tseries)
library(dplyr)

ui<-fluidPage(
fluidRow(dygraphOutput("forecast")))
dt1<-read.csv("C:/Users/dell/Downloads/archive (3)/daily-minimum-temperatures-in-me.csv")
  
server<-function(input,output,session){
  output$forecast <- renderDygraph({
  interval_value_formatter <- "function(num, opts, seriesName, g, row, col) {
  value = g.getValue(row, col);
  if(value[0] != value[2]) {
    lower = Dygraph.numberValueFormatter(value[0], opts);
    upper = Dygraph.numberValueFormatter(value[2], opts);
    return '[' + lower + ', ' + upper + ']';
  } else {
    return Dygraph.numberValueFormatter(num, opts);
  }
}"
  timeseies1<-ts(as.numeric(dt1$Daily.minimum.temperatures),start = c(1981,1),frequency = 12)
  
  timeseies1 %>%
  stlf(timeseies1, h = 36) %>%
  {cbind(actuals=.$x, forecast_mean=.$mean,
        lower_95=.$lower[,"95%"], upper_95=.$upper[,"95%"],
        lower_80=.$lower[,"80%"], upper_80=.$upper[,"80%"])} %>%
  dygraph(main="Date", ylab = "Daily minimum temperatures") %>%
  dyAxis("y", valueFormatter = interval_value_formatter) %>%
  dySeries("actuals", color = "black") %>%
  dySeries("forecast_mean", color = "blue", label = "forecast") %>%
  dySeries(c("lower_80", "forecast_mean", "upper_80"),
           label = "80%", color = "blue") %>%
  dySeries(c("lower_95", "forecast_mean", "upper_95"),
           label = "95%", color = "blue") %>%
  dyLegend(labelsSeparateLines=TRUE) %>%
  dyRangeSelector() %>%
  dyUnzoom() %>% 
  dyCrosshair(direction = "vertical") %>%
  dyOptions(digitsAfterDecimal = 1) %>%
  dyCSS(textConnection(".dygraph-legend {background-color: rgba(255, 255, 255, 0.5) !important; }"))
  
})
}
shinyApp(ui,server)

could any one please tell me why is it happening and how could i rectify this issue.

we don't have your csv, so we can only guess at the contents of this variable.

Therefore, could you please add representative data to your posting to make it a reproducible example (reprex)? Please have a look at this guide, to see how to create one: