Annotation position in scatterpolar are strange

Hello, I’m developping a small rendering of values in a scatterpolar. The labels on the values are too long, so, I display A, B, C etc as values label. Then, at the left of the chart, I add Annotations with A: xxxx etc to have proper long labels.
The Y position of the annotation is fine, e.f. 0.2 0.4 0.6 0.8 … BUT many lines are perfectly spaced and a few are not, reducing dramatically the space.
Anyone has an idea why the actual Y values are not properly respected ?
Annotation is like
align: ‘left’,
font: {
color: ‘black’,
size: 12
showarrow: false,
text: [${wRef.toString()}] : ${wLabVal.label},
x: wLabelsXPosition,
xref: ‘paper’,
y: wLabelsYPosition,
yref: ‘paper’