Inconsistent behavior of strip.switch.pad.grid and strip.switch.pad.wrap in ggplot 3.3.3

[KleinWurm]

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According to ?theme, strip.switch.pad.grid and strip.switch.pad.wrap have the same effect, i.e. "space between strips and axes when strips are switched (unit)". My intuitive understanding was to use strip.switch.pad.wrap with facet_wrap and strip.switch.pad.grid with facet_frid. However this is wrong according to the reprex below:

    library(ggplot2)
    p <- ggplot(data = iris, aes(x = Sepal.Length, y = Petal.Length)) + theme(strip.placement = "outside")

    p + facet_wrap(.~Species) + theme(strip.switch.pad.wrap = unit(10, "mm"))

    p + facet_wrap(.~Species) + theme(strip.switch.pad.grid = unit(10, "mm"))

    p + facet_grid(.~Species) + theme(strip.switch.pad.grid = unit(10, "mm"))

    p + facet_grid(.~Species) + theme(strip.switch.pad.wrap = unit(10, "mm"))

Session info:

R version 4.0.5 (2021-03-31)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 10 x64 (build 19042)

ggplot2 version 3.3.3