How do I remove the comma from the date in the sparkline tooltip?

I'd like to remove the comma from the date in the sparkling tooltip, but I need to keep it in the value. I don't fully understand the jQuery Sparkline formatting.

Sparkling tooltip example

library(shiny)
library(dplyr)

ui <- fluidPage(

  htmlwidgets::getDependency('sparkline'),

  DT::dataTableOutput("table")

)

server <- function(input, output) {

    raw_data <- data.frame(date = 2000:2021,
                     value = sample(100:500, 22))

  data <- raw_data %>%
    # Create the sparkline
    summarise("value" = sparkline::spk_chr(c(value),
                                xvalues = date,
                                tooltipFormat = '{{x}}: {{y}}'))

  output$table <- DT::renderDataTable({

    cb <- htmlwidgets::JS('function(){debugger;HTMLWidgets.staticRender();}')

    DT::datatable(data = data,
              escape = FALSE,
              options = list(drawCallback = cb))
  })

}

shinyApp(ui, server)

As defined here, you can set numberDigitGroupSep to empty string:

data <- raw_data %>%
    # Create the sparkline
    summarise(
        "value" = sparkline::spk_chr(
            c(value),
            numberDigitGroupSep = "",
            xvalues = date,
            tooltipFormat = '{{x}}: {{y}}'
        )
    )