add_footnote() add ^^ when I select notation='none'

Question

I need to add a footnote to tables generated with kable. The output file must be a markdown file. The only option I found is to use add_footnote as footnote function doesn't work with markdown. I just want to add a source to my table, so I don't need to have any symbol. When I use the option notation = 'none' to do not have any function I always have ^^ before my note.

This is my code :

    kableISPF <- function(dt, columsContainingPercentIndex=NA, digit=1, percentAccuracy=0.1, caption="Default caption", format="markdown", source="ISPF", note=NA){
  x <- copy(dt)
  if(!is.na(columsContainingPercentIndex)){
    cols=colnames(dt)[columsContainingPercentIndex]
    x[ , (cols) := lapply(.SD, FUN=function(x) percent(x, accuracy = percentAccuracy, decimal.mark = ",")), .SDcols = cols]  
  }
  alignChar <- paste0(c("l", unlist(rep('r', length(x)-1))))
  if (note!="NA"){note=sprintf("**Note :** %s",note)}else{note=""}
  kable(x,
        caption = caption,
        digits=digit,
        format.args = list(big.mark = ' ', decimal.mark = ','),
        align=alignChar,
        format = format, booktabs=T)%>%
        kable_paper(full_width = T,
                       lightable_options = "hover",
                       html_font="\"Helvetica Neue\",Helvetica,Arial,sans-serif")%>%
        add_footnote(label=sprintf("**Source : **%s",source),notation='none')
}

And I call it with (as exemple) :

kableISPF(POP.G2[Commune][[1]],c(2,3,4), 1, 0.1,caption = "POP G2 -  Population par grandes tranches d'âges",source = "ISPF - Recensement de la population",note = "NA")

Why do I have this behavior ? How to avoid ^^ characters ?

Thanks a lot for your help.