heat map - show data value option has been removed, because currently data labels for map or heatmap are not available regardless if this is ticketed or not
speedometer - label in the middle no longer has white background, it's set to transparent, so that text colours can be set to light colours
Guidelines for creating a dark theme:
There is no guarantee ways to find out if text is inside, outside, partially inside the data blocks, so there is really only one way to make text labels working well in dark themes:
use dark application background
use dark colours for chart data
use light (e.g. white) text for chart data, which can be defined as per the screenshot below