Easy Counter: Create Counters With Variable-Width Fonts
When using fonts that do not use fixed-width numerals, the resulting counter can shift on-screen as it adjusts to the variable width of the output.
Set the text alignment to Left, which anchors your counter to an edge:

This usually keeps the text stable. With very few fonts that extend far beyond the left and right edges of the line, it may be necessary to adjust Horizontal Padding too:

It might also be best to turn the Background off, to avoid having its size change too frequently and therefore flicker. In this scenario, it would be best add the background through a separate, static generator.