For anyone using variable fonts in Affinity design apps:
⚠️ BEWARE ⚠️

Affinity applies kerning values from a variable font’s default instance (usually a moderate “Regular” style) to *all* variants of that font, even if it includes design variants with drastically different kerning.

It’s easy to miss in variable fonts with relatively limited stylistic ranges (where kerning doesn’t change much throughout), but it’s quite problematic for variable fonts that cover more expansive ranges of variation.