When making a gradient, Figma chooses to move linearly in the sRGB colorspace. This produces gradients that can appear strange—for example, a saturated red-to-green gradient will appear darker in the center than at either end.
The ability to use a perceptual interpolation for gradients, like OKLab, would help a lot.
I’m very reluctant to use these—the results they produce are approximately correct (although they’re still stuck with CIELAB and CIELUV) but they don’t produce a single gradient or image—what they actually do is produce a faux-gradient composed of several linear sRGB sub-gradients that interpolate between points in the desired gradient.
This causes strange banding artifacts, and isn’t suitable for production use.