R : object in custom function is not found for specific usage - r

Question

I face a problem with R (and its well known rigor in dealing with objects...) : I wrote a custom function to plot dotplots from ggplots and add a custom p value with brackets. The problem is not the plot (it works well...) but dealing with objects and functions : I cannot use an object created inside the function. Some code to explain :
pval.label <- function(p)
{
if (p < 0.001) { return("p<0.001") }
else { return(paste0("p = ", round(p, digits = 2))) }
}
dot_plot <- function(data, var, endpoint, title, ylab)
{
endpoint = deparse(substitute(endpoint))
var = deparse(substitute(var))
df = data.frame(var = data[[var]], endpoint = data[[endpoint]])
pvalue = compare_means(data = df, formula = var ~ endpoint)
pvalue <- pvalue %>% mutate(y.position = 120*(max(df$var)/100))
plot =
ggplot(df, aes(x=endpoint, y=var)) +
labs(title = title, y = ylab, x="") +
geom_dotplot(binaxis='y', stackdir='center', stackratio=1.7, binwidth = .8, show.legend = F,
aes(fill = endpoint, color = endpoint)) +
stat_summary(fun=median, geom="crossbar", lwd=.5, width=.7, col="black", show.legend=F) +
scale_fill_manual(values=c("#2d419b", "#ee2025")) +
scale_color_manual(values=c("#2d419b", "#ee2025")) +
theme_classic() +
theme(text = element_text(family = "sans", face = "bold"),
plot.title = element_text(size = 14, hjust = .5, lineheight = 1.5),
axis.text = element_text(size = 12, face = "bold", colour = "black"),
axis.title = element_text(size = 14, face = "bold", colour = "black"),
axis.line = element_line(size = 1),
axis.ticks = element_line(size = 1), axis.ticks.length = unit(5, "pt")) +
stat_pvalue_manual(pvalue, label = "{pval.label(pvalue$p)}", bracket.size = 1, size = 4)
plot
}
The problem is with this line :
stat_pvalue_manual(pvalue, label = "{pval.label(pvalue$p)}", bracket.size = 1, size = 4)
It says the object "pvalue" is not found. But, if I create this object outside the function and have it in R environment, it works well !!
How to explain that ? And how to deal with it ?
Thanks,
Olivier