Should the series of 1821 start at 0 instead of 21?
library(feasts)
#> Loading required package: fabletools
lynx_tsbl <- as_tsibble(lynx)
gg_season(lynx_tsbl, value, period = "40 year")

forecast::seasonplot(lynx, 40, type = "l")
#> Registered S3 method overwritten by 'quantmod':
#> method from
#> as.zoo.data.frame zoo

Created on 2020-07-27 by the reprex package (v0.3.0)
Should the series of
1821start at 0 instead of 21?Created on 2020-07-27 by the reprex package (v0.3.0)