This is in the dev version, so Bioc 3.20:
example(importDittoBulk, echo = FALSE)
myRNA
# Basic dittoplot, with jitter behind a vlnplot (looks better with more cells)
dittoPlot(object = myRNA, var = "score2", group.by = "timepoint", adjustment = NULL)

Looks identical with z-score adjustment (or relative.to.max).
dittoPlot(object = myRNA, var = "score2", group.by = "timepoint", adjustment = "z-score")

Works fine for genes though:
dittoPlot(object = myRNA, var = "gene1", group.by = "timepoint", adjustment = NULL)

dittoPlot(object = myRNA, var = "gene1", group.by = "timepoint", adjustment = "z-score")

Note that it is still applied to genes when both metadata variable and genes are provided, e.g.:
multi_dittoPlot(myRNA,
vars = c("score1", "score2", "gene3", "gene4"),
group.by = "clustering", adjustment = "z-score")

Probably won't have any time to chase this one myself for at least a few weeks.
This is in the dev version, so Bioc 3.20:
Looks identical with z-score adjustment (or relative.to.max).
Works fine for genes though:
Note that it is still applied to genes when both metadata variable and genes are provided, e.g.:
Probably won't have any time to chase this one myself for at least a few weeks.