Customization: hovertemplate behavior

[eagleco]

I'm trying to customize hovertemplate but whatever I set seems to get %{customdata.name} : added in front of it, am I missing a configuration option or is there some other way to prevent this? See yellow and red boxes below for an example

I poked around a little bit in plotly-graph-card.ts but my js is pretty weak. I see where the default template is set but can't figure out why the name : still gets added when I provide a template?