Fonts turn to be blurry in MacOS - Xquartz when enable showtext

[mingsu]

require(showtext)
showtext_auto(enable = F)
plot(1)

showtext_auto(enable = T)
plot(1)

When I setup the dpi, font size changes

showtext_auto(enable = T)
showtext_opts(dpi = 220)
plot(1)

> sessionInfo()
R version 4.0.2 (2020-06-22)
Platform: x86_64-apple-darwin17.0 (64-bit)
Running under: macOS Catalina 10.15.5

Matrix products: default
BLAS:   /Library/Frameworks/R.framework/Versions/4.0/Resources/lib/libRblas.dylib
LAPACK: /Library/Frameworks/R.framework/Versions/4.0/Resources/lib/libRlapack.dylib

locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

other attached packages:
[1] showtext_0.9   showtextdb_3.0 sysfonts_0.8.1

loaded via a namespace (and not attached):
[1] compiler_4.0.2
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