Clicking a hyperlink and come back the origin web it wiil connect again or the interface blurring

There are sevreal links in my shiny app web.

It always reload or the interface blurring when I go back the web after clicking a hyperlink.

Just like this:

I know it's necessary for me to solve it.But I don't know where the wrong with my code or it is some problem with shiny app server ??

Here is my sample code:

library(shiny)
library(dplyr)
library(tidyr)
library(ggplot2)
library(gridExtra)

mean_data <- data.frame(
  Name = c(paste0("Group_", LETTERS[1:20])),
  matx <- matrix(sample(1:1000, 1000, replace = T), nrow = 20)
)
names(mean_data)[-1] <- c(paste0("Gene_", 1:50))

sd_data <- data.frame(
  Name = c(paste0("Group_", LETTERS[1:20])),
  matx <- matrix(runif(1000, 5, 10), nrow = 20)
)
names(sd_data)[-1] <- c(paste0("Gene_", 1:50))


###
ui <- fluidPage(
  
  pageWithSidebar(
    headerPanel("123"),
    sidebarPanel(
      selectInput(
        "selectGeneSymbol",
        "123:",
        choices = colnames(mean_data)[-1],
        multiple =F,
        width = 400,
        selected = 1
      ),
      
      actionButton(inputId = "plot1", label = "FPKM"),
      tags$h6(tags$a(href="https://www.ncbi.nlm.nih.gov/", "link"))
    ),
    mainPanel(
      plotOutput("plot")
      #uiOutput("all")
    )
  )
  
)

server <- function(input, output, session) {
  
  ## put sd into mean_data
  plotdata <- eventReactive(input$plot1, { 
    df <- mean_data %>% mutate(sd = sd_data[,input$selectGeneSymbol])
  })
  
  p1 <- eventReactive(input$plot1, {
    ggplot(data = plotdata(), aes(x = Name, y = .data[[input$selectGeneSymbol]], fill=Name,
                                  ymin = .data[[input$selectGeneSymbol]] - sd, ymax = .data[[input$selectGeneSymbol]] + sd )) +
      geom_bar(stat = "identity", position = position_dodge(0.9), width = 0.9) +
      # geom_errorbar(aes(ymin = plotdata()[,input$selectGeneSymbol] - sddata()[,input$selectGeneSymbol], ymax = plotdata()[,input$selectGeneSymbol] + sddata()[,input$selectGeneSymbol]), width = .2, position = position_dodge(0.9)) +
      geom_errorbar(width = .2, position = position_dodge(0.9)) +
      theme_classic2() +
      rotate_x_text(angle = 45) +
      theme(legend.position = "none") +
      labs(title = input$selectGeneSymbol, x = NULL, y = "123_value")
  })
  
  output$plot <- renderPlot({
    p1()
  })
  
}

# Create Shiny app ----
shinyApp(ui = ui, server = server)

Can you give me some advice ro solution ?? It's vital for me to deal with it.