IMHO this should work, at least in latest snapshots …
formatter: =v=>v.toFixed(2)
Did try only on a gauge, but probably should work for all …
EDIT: syntax for bar is a bit different:
label:
show: true
formatter: =v=>Number.parseFloat(v.data[1]).toFixed(1)
this did the trick for me
or with toFixed(3):
