How do I prevent that plot_gg displays edges of polygons (is this a bug?)

[ghost]

(also discussed on StackOverflow where it was suggested that this may be a bug in Rayshader) https://stackoverflow.com/questions/75121533/rayshader-how-to-prevent-that-plot-gg-displays-edges-of-polygons

When I set panel.background to white, plot_gg shows the edges of the polygons from my data. These are not shown by ggplot nor when I set panel.background to black. Or even when I don't set a panel at all.

Is this a bug in plot_gg or am I missing something? (changing the crs from 28992 to 4326 does not make a difference)

Reproducible code (as copied from StackOverflow):

library(ggplot2)
library(rayshader)
library(sf)    

temp <- tempfile()
download.file("https://www.cbs.nl/-/media/cbs/dossiers/nederland-regionaal/vierkanten/500/2022-cbs_vk500_2021_v1.zip", temp)
NLD <- read_sf(utils::unzip(temp, "cbs_vk500_2021_v1.gpkg"))

#NLD <- NLD[-c(99:nrow(NLD)),]                # enable for faster testing 

NLD$aantal_inwoners <- ifelse(NLD$aantal_inwoners < 0, 1, NLD$aantal_inwoners)

kaart <- ggplot(NLD)+
  geom_sf(aes(fill=aantal_inwoners), colour=NA) +
  scale_fill_gradient(high="deeppink", low="black") + 
  theme_void() +
  theme(legend.position = "none")

#This second part is required to keep a white background in plot_gg (otherwise it is black). 
kaart <- kaart + theme(panel.background = element_rect(fill="white", color="white"),        
                       plot.background = element_rect(fill = "white", color="white"))

kaart

plot_gg(kaart, width = 3, height = 3, multicore = TRUE, 
        zoom = .7, theta = 0, phi = 90, windowsize = c(800, 800))

This is what is produced by ggplot:

And this is what is produced by plot_gg:

This data shows the distribution of the population in The Netherlands in squares of 500x500 m.