Small Caps disable Figure Styles

[Lululalu]

In the screenshot below, small caps and old style figures are enabled in different fonts. Having small caps enabled disables the old style figures in Source Serif 4.

[frankrolf]

Deliberate. Source Serif contains small cap figures, which you see in your screenshot.

[frankrolf]

FWIW, I find the mixing of old-style figures and small caps questionable – small caps are inherently descender-less, old style figures are to be used in mixed-case context.

[moyogo]

While this may disagree with some users’ expectations based on what other fonts do, one can disable the small caps feature on figures if they want to avoid this behaviour.

Note that some writing systems use 3, 7 or 8 as letters and some users may prefer one specific behaviour. It's not clearly a one solution problem.